How potential energy changes when you pull a magnet off a refrigerator door

The potential energy increase.

Explanation:

Potential energy is the energy stored within a physical system. Energy is the ability to do work or cause movement.  A free system acts in the way that minimizes the potential energy, so when you pull a magnet off a refrigerator door you are increasing the potential energy of the system because now if you allow the magnet to move freely, it will snap the door to minimize PE.