Tennis racquet handle size question?

I have a prince EXO3 tour series. Ive been hitting with it for about a year and i think the handle is too small. Its size is a 2. (im pretty sure, if it turns out im wrong i will dit this!) The racquet always twist in my hand. I just learned 3 min. ago that if the raquet twist in your hand then the grip is too small. I always thought it was me (which it still might be). anyways, the racquet was very expensive and I can't afford to buy another one. How can I make the handle bigger?? I was thinking about putting another replacement grip over to try and fatten the grip up. would that work??