like Bob said, you can back bend it some but adding a new back to a bow with a damaged belly seems unproductive to me. You could reduce the belly side some and add a belly lam or even toast the belly while the bow is in a reflex form...but is it worth it?
What is the draw weight now and what do you want it to be when you're done? In most cases I think a new bow would be more appropriate than trying to fix the old one. The bow was overstressed and took set at the draw it was originally tillered too. Stressing it more isn't gonna make it a better bow.
