How to crisp breaded foods the next day (especially panko)
Reheating fried food is extremely challenging.  

The least bad method is probably baking in a slow oven, about 250-300 F.  You want to reheat only enough to get the food warm enough to enjoy, but not so piping hot that it would trigger additional browning.  

At these low temperatures, you should not get too much additional browning, although you will never have the ideal crispy texture that first-fried foods have.