Can meatloaf be made ahead and then reheated in the oven?

Yes of course. That is called "canned food". It is rather demanding because you have to be sure your hands and your dishes are absolutely clean, then you transfer the food to its container and seal it while it is still quite hot. I use Zip-Loc brand plastic cups with snap-on lids to hold individual servings and they stay good for months if I take that long to eat them.

I prefer to make meatloaf with mushroom gravy.