I'm not sure what your feeding routine or schedule is, but off the top of my head:
1) feed later in the evening when the snake is awake.
2) Since it seems you are feeding live keep the mouse in a small container with air holes near or on top of the enclosure so the snake can smell it for a while and get in the mood.
3) If you are feeding every 5 days try switching to 7 days. If you feeding every 7 days try switching to 9 or 10 days.
4) If you are using a tank and it has alot of open space, you may need to add a little more clutter or cover 3 sides of it, if you haven't already done so...