Microwave. The easiest and fastest way to reheat is to place them in a covered dish and heat them in the microwave at half-power for 4-5 minutes, stirring occasionally. Stovetop. Let potatoes thaw overnight in the fridge, and place in a large pot on low to medium heat. Stir until heated through. Slow cooker. Thaw potatoes overnight in the fridge and heat on low for 2-4 hours. Add more cream cheese, whipping cream, or even sour cream to make it more creamy after reheating.