How to reheat ham pot pie

If this dish is what I think it is... essentially rolled dumplings or pasta in a thick broth with meat and vegetables (which is the chicken pot pie at my local itinerant Dutch market is like), yes you can make it in advance and reheat it. If you do need to reheat it, this is one case where a microwave (and occasional stirring) will actually perform quite well; heating it in a pan in a slow oven (covered with foil) should also work nicely with minimal risk of scorching.

The problem is, the dumplings are likely to absorb more of the broth over time and become mushy if you hold and reheat the dish.

You are almost certainly better off prepping your components, and actually cooking the dumplings or noodles (whatever you want to call them) the day you are going to eat it, if that is reasonably practical.