Preheat the oven to 400°F (200°C)
Spread the fries in a single layer on a baking sheet
Bake for 5 to 10 minutes, flipping once halfway through
Heat a skillet over medium heat
Add a small amount of oil to the skillet
Add the fries in a single layer
Cook for 3 to 5 minutes, stirring occasionally
Use an air fryer at 375°F (190°C)
Heat the fries for 3 to 5 minutes, shaking halfway through
Microwave only if needed
Place the fries on a microwave-safe plate with a paper towel
Heat in short intervals until warm
Serve immediately after reheating