If you are like me, saving every pot that you can just comes naturally. Now you have plenty of last year's pots to fill and are wondering if you need to do anything before refilling with potting soil. Usually when refilling pots, it is a matter of inspecting, washing in soapy water, and sanitizing by drying in sunlight. Pots being reused for more than one year need to be checked that the plastic is still strong enough to hold the weight of your planting. Most plastics become brittle and weak over time, from sunlight exposure.