You're correct that it's better not to re-freeze rodents. If he's fed 3 times with you, he may well be going into a shed cycle, & in that case, you're better off
waiting as he is likely to refuse anyway. Waiting a few days won't hurt...snakes are designed NOT to eat all the time as we are so get used to that. They have
no "scheduled" meals in the wild...prey doesn't show up at certain intervals. It does sound like your mice are too small...he should be ready for hoppers
at the very least.