Q:

How to add More CPU Core and RAM in Running VM Instance

I need to add more CPU Core and RAM in Running VM Instance. Is there any way i can do that?

A:

This is no longer the best way (as of 2016).  Now the easiest way to do it is to stop the instance, then click on edit and change the machine type to what you want—you can even customize it.  Once done, just hit start and it'll come back up with the new type you've selected.
There is no longer a need to clone it to grow it.

A:

you can't dynamically change RAM and CPU values of compute Engine Instances, but you can create a snapshot of instance and create a larger instance from the snapshot.

