While it's more labor-intensive, the best way to reheat crab is to boil the legs, heating the meat without impacting its texture. To start, put the crab in a pot of boiling water.
Let them heat up for about five minutes, and rotate the crab with tongs halfway through the process. Boiling will ensure the crab meat remains moist and soft.
You can also steam the crab so the meat retains moisture. Use your oven by placing the crab into an oven-safe baking dish with a small amount of water.
If you need to heat the crab meat quickly, use the microwave. Place a slightly damp paper towel over the crab and cook it for about a minute to reach the ideal temperature.