As lillia, CC'ing her is of paramount importance. Use your Q to knock her up when possible. Once she is CC'd, beat her up. 

Watch out for early healing reduction from her end in this matchup. Not doing so can allow Lillia to outduel you.

Lillia will have a tendency to poke you and your allies from a distance and then ult and go for the kill. You may want to use your Flash, or the fog of war to go for the enemy team in such a case. This way, your team can deal with Lillia as they wake up while you can use your abilities to zone off the enemies.

Keep the wave close to your tower and just focus on farming. Remember to stay away from terrain as it can let her splash her E. As lillia, The CC'ing is of paramount importance. Use your Q to knock it out when possible. Once it is CC'd, beat it. Pay attention to the reduction of early healing of its end in this matchup. Do not do it can allow Lillia to surpass you. Lillia will tend to you and your allies at a distance and then ult and go to kill it. You can use your Flash, or the fog of war to go for the enemy team in such a case. In this way, your team can deal with Lillia as they wake up while you can use your abilities to land the enemies. Keep the wave near your turn and focus on agriculture. Remember to stay away from the ground as it can let her splash her E.