Yes, it’s safe to reheat cooked chicken but it’s advised not to reheat it more than once. Therefore when you are planning to eat your leftovers reheat only the amount you can eat in one sitting. Reheat the meat properly so it reaches the recommended temperature of 70 C for 2 minutes and it’s hot all the way through.    Do not freeze or refrigerate any reheated leftovers, all this warming up and cooling down is increasing the risk of growing bad bacteria and food poisoning.