Repartitioning Internal Memory of Android Device
You can repartition the internal memory. In essence it can be done, but what many others have answered is basically correct. Not only is it quite difficult and risky to perform it, it also requires specialized skills which the average user may not have. There is one solution to the problem though.

The easiest way to do this is to look for a custom ROM for your phone. Many custom ROM providers recognize the issue already and have a fix for it in some way or the other.

Your phone model can provide more information if you like.