I just repaired a stripped out caliper bolt hole this weekend using a Perma-coil kit. The caliper bolt is M8x1.25. The instructions said to drill the hole out to 21/64, tap the hole with the supplied tap, then install one of the inserts. Worked great and was super easy too.
So if the hole is no bigger than 21/64, you can use the Perma-coil kit. If the hole is already bigger than 21/64, you can get the next biggest kit, which I believe is M9x1.25, and get a new bolt. But you'd have to do as cruzmyxj said and drill out the sleeves.