I agree with Judy in that a lot of times it is something in the husbandry that is causing the snake to go off feed....

I also think it's a great idea to start monitoring the weight of the snake to be sure that weight loss isn't happening without you being aware of it.

Other than that, I think I would offer a live prey item to the snake every 7 days. Mice take a while to get up to the size of a small rat and so you could hold them over from week to week without running the risk of it getting big enough to star in a science fiction movie!