Have you done a property walk around?
Do you see shingles, bits of insulation etc on the ground? That usually indicates squirrels, raccoons, etc. If you have fence posts that butt up against the house, lay down some spike strips. It doscourages climbing.
Mice tend to come back into homes in the November/December time frame.
This laid outside:
http://tomcatbrand.com/product/6-ultra-1-oz-block-bait
work's well. It also has the ability to kill large rodents like squirrels and raccoons. Keep cats and dogs away from it, because it can seriously sicken them.