Graft it. Quickly. Go find a peach tree of a variety you like; or buy one at a nursery, plant it, and take a trimming for the old tree. You will have two then.
Get a leaf branch that is approximatly the same diameter as the young 'trunk' left in the ground. Do a four way split or banana splice and tape it on with grafting tape or electrical tape. Don't lose those established
roots! Graft something on to them. By the end of the season you will have almost recovered the growth.