The most effective way to reheat prime rib is to warm it in an oven at a low temperature until the beef reaches the desired serving temperature. The ideal oven temperature for reheating prime rib is between 200 and 250 degrees Fahrenheit.
A microwave is also an effective tool for reheating prime rib. Care must be take not to leave the beef in a microwave oven too long to avoid drying the prime rib. Setting the timer to 1 minute initially and then cooking it for additional 30-second intervals until the meat reaches the desired temperature is an ideal course to follow when reheating prime rib in the microwave.