Leftover popcorn doesn't have the same crunch factor as fresh popcorn, but instead of throwing it away, you can revive its texture by reheating it in your air fryer.
An air fryer is essentially a small convection oven, so the heat reaches all sides of the popcorn. This evenly re-crisps old popcorn better than other reheating methods can manage.
Depending on how much butter or oil your leftover popcorn already has, you may or may not need to add additional fat. A spritz of oil can crisp it more and help seasonings stick.
The cooking time may vary depending on your air fryer, but it only takes about two or three minutes. Avoid overfilling the basket and be sure to give it a shake every minute or so.
The heating element above the basket can catch your popcorn if the hot air sends it upward. Avoid heating unpopped kernels from scratch, as they can get caught in it and burn.
Reheating already-popped corn is not likely to have as much activity, but watch out for any unpopped kernels in your leftovers and stay close by to check them while heating.