Once polenta has cooled, or if you're using leftover polenta that's been stored in the fridge, you have a few options for reheating it. It will likely be a solid block. If you'd like to cut the polenta into blocks, you could always fry it up in a pan with a touch of butter or oil. Or, if you want soft polenta, mix a bit of water with it and warm it over low heat on the stovetop, stirring constantly to ensure it doesn't stick and burn to the bottom of the pan. You can also reheat the polenta in the microwave by adding a bit of water, and stirring it periodically as it heats to get that creamy consistency.