There are a few ways to reheat rice to retain the moisture, but the best is probably to put it in the microwave.
In a microwave safe bowl, put in your rice and add a few tablespoons of water. Then cover it with a plate so that it works like it’s being steamed. Put it into the microwave for a minute and take it out and mix it up. If it needs to be hotter, add a little more water and then heat it up again.
Hope this helps!