Storage and reheating. Store leftover grilled chicken thighs in an airtight container in the fridge for up to 4 days. Reheat gently in the microwave or in a covered skillet over low heat with a splash of water or broth to keep them moist. For longer storage, freeze the cooked chicken in a freezer-safe container for up to 3 months. Thaw overnight in the refrigerator before reheating.