replace the scope base
If you can replace the base with a weaver rail that has the slots, I would do that to make sure it doesn't happen again. You could always have a slot machined in it for each ring as well.
I have used epoxy on the back of the rings though and had very good success with this as well. Make sure to roughen up the area with 300 grit paper and then degrease it. I use bedding compound, but most any good 12-24 hour gel type epoxy will work for you. Mix it up and use a tongue depressor or plastic knife or whatever you have to place a decent size dallop behind each ring on both sides. Once it has dried, I use my dremel type tool to remove most of the excess. I would advise you to either use a clear epoxy or one that can be dyed black or is black to help hide it though.
Just have it rebore sighted and then dial it back in once you have the change over or repair done on it.