Stove: You can reheat large batches of Italian Soup on the stove over medium low heat, stirring occasionally until warm.  You will need to add some additional broth or half and half/cream to the soup because some of the pasta will absorb it while sitting overnight. Microwave: For smaller batches or individual servings, you can use the microwave.  Transfer soup to a microwave-safe dish, cover with a microwave-safe lid or paper towel.  Microwave for 2 minutes, stir, then continue to microwave for 30-second intervals, if needed.  Stir in additional broth, half and half or cream to reach desired consistency.