Leftover rice should be allowed to cool completely, then stored in a glass or plastic container or a plastic bag, well sealed, in the refrigerator. Most rices harden slightly when refrigerated, but sticky rices tend to get very hard and are then difficult to revive the next day. Consequently, we do not refrigerate leftover sticky rice (anyway, there are rarely leftovers). Rice will keep in the refrigerator for three days, but is best used within twenty-four to thirty-six hours.
To reheat rice, place it in a heavy pot with several tablespoons of water. Break up any lumps with wet hands or with a wooden spoon. Heat over medium heat until you hear the water boiling and see steam rising from the pot. Stir gently, lower the heat, cover, and let steam for 3 to 5 minutes, stirring once or twice. Alternatively, place the rice in a microwaveable container with a tight-fitting lid. Add a little water to the rice, break up the lumps as above, then cover tightly and place in the microwave oven at full power. Depending on the quantity of rice and the size of your oven, it will take one to two minutes to reheat. Be careful of hot steam when you open the lid of the container.