I agree, there is no way to punish the dog after the fact. You have to do it right after he comitted the act.

As for the OP, I would obviously take care of all expenses they had for the vet. Let them know you are sorry, and will be there when they are ready to talk. Dont get too pushy, chances are they wont want to talk to you right now. When the time comes offer to buy a new bunny.