Preheat machine to 375 degrees (if you only have even temps set to 380).
Spray some oil on the outside of the skin to help it crisp up a bit during reheating. Since you're only heating up the chicken you don't have to worry about the internal temperature.
Start with 6 minutes flipping halfway through and then cut open and feel the insides, longer with bone in pieces. If you want to add sauce, brush it on after flipping it over.
You can add more time beyond that, just enough to get the middle warm, but don't want it to dry out.