I put them in hot water until they're totally thawed, it will depend on the size of the feeder as to how long it will take for it to thaw. I then heat it up with a hairdryer right before I offer it to my snakes so they have a good hotspot on the feeder to aim for (I heat the heads up). I personally don't recommend refreezing already thawed feeders because there's a better chance of the feeder falling apart next feeding (the tissue becomes weak once the meat is thawed then re-frozen) so I just toss them. Always toss them if you leave the feeder in with them overnight IMO.