There is more to it than just glueing another layer of glass over existing glass. You would have to built a form that matches the bow. Then the bow needs to be heated to 160 deg to cure the epoxy,which could cause delamination of the existing glass, or do a slow cure for several days. Then you would have some very heavy mass weight limbs that would off set the draw poundage gain. You could sand off the existing glass, but I think it would be dificult to tell when you have gone past the glass and into the wood laminations. You could also just cut the limbs off and build new limbs on to the riser, but you may as well start from scratch.