My corns don't generally refuse, but if they do, there's usually another corn just waiting to have a second course, so... the pinks/small mice take care of themselves.
Rats, however, are a different story (for the BPs)... The rats get refrozen once (I also don't leave rats in with my BPs... they all get fed outside of their cages and I have to dangle it and trick them), and then if not eaten, they WOULD get tossed. However, I have never had a rat go more than one refreezing (probably because after it's been frozen once it gets immediately offered to my BP that will not turn down a meal).