I don't let them go more than a month without eating one way or another until they're over 250 grams or so. I would try a live feeding at this point. If you can't get a live rat of the right size, your snake should be able to take down a small mouse relatively safely. I would keep a pencil nearby in case the mouse is able to get its mouth to the snake.

Sometimes you definitely need to wait them out a bit on the F/T, so don't be afraid to let them go a while between feedings. I just personally wouldn't go more than a month or 5 weeks.

GL