Allow frozen meatballs to thaw overnight in the fridge before reheating. To reheat, place the meatballs and sauce in a saucepan with ¼ cup of beef broth or water and then cover with a lid. Heat the skillet over medium heat for 20 to 30 minutes, stirring every 10 minutes, or until warmed through. If the sauce gets too thick as you reheat, you can turn the heat down to medium low. Note: If you feel like the sauce is getting too thick as the meatballs reheat you can turn the heat to medium low.