How to Repot a Plant
To repot a plant, start by filling the new pot with soil. However, take care to leave at least 1 inch between the plant's roots and the rim so there's enough room to water it. Then, water the plant before trying to remove it from its old pot, since the roots will come out easier if they're moist. Once you've removed the plant, prune some of the old roots, then place the plant in the center of the pot. Finally, fill in the edges with soil and water the plant to help the roots take nutrients from the new soil.
Choose a slightly larger pot. If you're repotting your plant into a new pot, choose a pot that is 1 to 2 inches larger in diameter and 1 to 2 inches deeper than the plant's current pot. If you choose a pot that has dimensions larger than this, the roots will need to grow into the pot before the plant itself can begin to grow. In other words, the plant has to grow all the way down before it can grow upward. Choose a pot with drainage holes. When you're selecting a new pot, make sure it has drainage holes to allow excess water to drain. Even if you select a pot that is the correct size, you still don't want water sitting in the bottom of it and causing root rot. Clean and disinfect the pot. It's important to disinfect old pots before reusing them, as they can accumulate minerals or other debris that are detrimental to plant growth. Mineral salts, for example, can dehydrate your plant and keep it from flourishing. Other debris can harbor disease-causing organisms. To disinfect your pot, soak it in a solution containing one part bleach and nine parts water for at least ten minutes. Place it in a solution of water and dish detergent and then rinse. To clean mineral deposits and debris from a steel pot, use steel wool or a wire-bristle brush to scrub them away. Plastic pots only need a scrubbing pad. You can scrape off any remaining deposits with a knife. Once you've cleaned the pot, rinse it with water and then soak it until ready for use. Soak the new pot. If you decide to use a terra cotta pot for repotting, make sure you soak the pot in water for a few hours before you begin the repotting process. Terra cotta is pretty porous, which means it soaks up water easily. You don't want your pot stealing your plant's water. Cover the drainage holes. It's important to have a pot with drainage holes, but you also want to make sure soil can't escape through them. Cover the drainage holes with something that will allow water to pass through, like paper towel or a coffee filter. Using a porous material like paper towel or a coffee filter over the drainage holes will allow water to pass through so your plant doesn't drown, but it slows down the process so the water can actually soak into the soil and help your plant. Put a few inches of soil in the new pot. You'll need a base of soil under the plant so the roots have something to grow into. Don't overfill the pot before you put the new plant in – the roots need something to grow into, but you also want them to be down far enough into the pot that they don't stick out of the top. Water the plant. Your plant will come out of its old pot more easily if the rootball is moist. You'll want to water the plant a few hours before you want to repot it. This will help it maintain its health even if it loses a root or two during the repotting. The rootball is the part of the plant that extends into the actual pot. It's made up of roots and soil and often keeps the shape of the pot after it's removed Remove the plant from its current pot. Place your hand over the top of the pot, and place your thumb and index finger around the plant's stem. Then turn the pot on its side and gently work the plant back and forth until it comes out. If the plant won't come out after several tries, you can use a knife to cut around the edge of the soil and try again. If you happen to break some of the roots, don't worry, you'll need to prune the rootball anyway. Prune the rootball. To make sure your plant takes to its new pot, you'll want to remove some of the old rootball to expose fresher roots to the new soil in the new pot. Clip off roots that hang below the rootball and make three or four slits in the bottom of the rootball about a third of the way up. If the rootball is black or smells, your plant might have some kind of fungal disease. You might not be able to save this plant or repot it. You can also shave away roots that seem particularly thick on the sides of the rootball. Untangle the remaining roots. Once you prune the rootball and have exposed the healthy roots, untangle some of the roots that are left over. This gives the roots more contact with the new soil in the new pot. It encourages the roots to grow outward, instead of around the rootball. Add some soil. You'll first want to add some soil to the pot to give your plant a place to sit. Make sure that the top of the plant's rootball will be no less than one inch below the rim of the pot, so that it won't overflow when watered. You can even measure, to verify. Place plant in new pot. As you place the plant into its new pot, center it by looking down on it from above and making sure it's not closer to any one side of the pot than the others. You also want to make sure it's sitting upright. While looking at the plant from the side, spin the pot and make sure the plant isn't tilted in any one direction. Fill the pot. Once you've placed the plant in the new pot, you'll want to put soil into the pot around the rootball. Don't overfill the pot - the soil line should be about 1” below the top of the pot. You can “stuff” or “fill” when you're adding new soil. “Filling” just means pouring soil in, around, and on top of the rootball. “Stuffing” means pouring the soil in and then pressing it down. You might want to “stuff” the pot for a top-heavy plant, because it will help you keep the plant steady and even. Water the plant. Once your plant is in its new pot and you've filled the pot with soil, water the plant. It will help the plant's roots soak up the nutrients from the soil and ensure that the plant takes to the new pot. You might need to add more soil to fill in empty spots once you water the new plant and the soil settles. It's also best to keep the plant out of the sun and high humidity after repotting. Don't fertilize it immediately, either. 
Choose a slightly larger pot. Choose a pot with drainage holes. Clean and disinfect the pot. Soak the new pot. Cover the drainage holes. Put a few inches of soil in the new pot. Water the plant. Remove the plant from its current pot. Prune the rootball. Untangle the remaining roots. Add some soil. Place plant in new pot. Fill the pot. Water the plant. 