Betcha anything it's too cool on the inside. As soon as she senses that, out it comes. Try heating in hot tap water until the outside measures about 100 degrees. I would also weigh each meal and keep track of how much she's taking, or not taking, each time. If necessary, try going down to 1% of body weight to get her started again. I think it would be a shame to go to live since she's hitting on the f/t, but that would be a good last resort. Good luck!
PS - IMO rats are better than mice.