The rules about reheating food are simple.
You can reheat any food (except cooked rice) as many times as needed, but make sure it is hot right the way through every time.
Cool any food you want to reheat as quickly as possible and put in the fridge as soon as it is at room temperature.
When reheating using a microwave oven, there may be uneven heating. Split heating session in two or three and move item position (e.g. pies, sponges) or stir well (e.g. soups, casseroles, stewed fruit) between bursts of heat.
Only heat cooked rice once. Rice can contain a bacteria; once the rice is cooked, the bacteria grow in the moist, warm rice and produce a toxin that survives further cooking. So if you're not
going to eat rice straight after you've cooked it, then you need to
store it in the fridge – as soon as possible, but definitely within four
hours. Refrigeration won't kill the bacteria but it will slow down its
growth – any uneaten rice should be thrown out after three days in the
fridge.
Links to further information http://www.abc.net.au/health/talkinghealth/factbuster/stories/2009/01/27/2475255.htm and http://www.typesofbacteria.co.uk/bacillus-cereus-cereals-rice.html
