Yes, you can reheat gravy after 2 days, but it is best to reheat it in a saucepan on the stove. Always bring the gravy up to a boil before consuming and check that it has reached an internal temperature of 165°F or higher. Alternatively, you can reheat gravy in the microwave for 1-2 minutes, stirring occasionally. Be sure to use a shallow glass or microwave-safe dish when reheating gravy in the microwave.