How to keeping fried leftovers crispy:

The key is using high, dry heat to drive off moisture and re-crisp the fried coating.

Reheat in the oven or toaster oven: Preheat to 400°F (200°C). Spread the fried leftovers in a single layer on a baking sheet or oven-safe wire rack set over a baking sheet. This allows air circulation for crisping. Heat for 5-10 minutes, flipping halfway, until heated through and crispy again.

Use the air fryer: Air fryers circulate hot air to re-crisp foods. Preheat the air fryer to 375°F (190°C) and cook the leftovers in a single layer for 3-5 minutes, shaking the basket occasionally.

Fry again briefly: You can re-fry leftover fried foods for 30 seconds to 1 minute in hot oil (350°F/175°C) to re-crisp the exterior. Drain well after.

Microwave then oven: Microwave first to make the insides hot, then oven bake for a few minutes to crisp up the outside.

Reheat on the stovetop: Heat a skillet over medium-high heat, add a light coating of oil, and pan-fry the leftovers for 1-2 minutes per side until crispy.

Don't sauce until serving: Wait to add any sauces or toppings until after reheating so the coating doesn't get soggy.

Let it rest: Once reheated, let the food rest for 1-2 minutes before eating so the coating can re-crisp.