Best to get rid of it and use fresh potting compost - if you have a garden, distribute it over the borders, or put it in the compost heap. You could rejuvenate it next year by adding something like Vitax Q4, but you run the risk of infection or infestation from nasties living the soil in the pots currently.

The very fact the pots have sat empty this year and even weeds haven't really grown in them tells you that the compost has little in the way of nutritional value. Spread it around as a mulch or put into your compost heap.