I've had really good success reheating ribs the day after cooking. I wouldn't go much longer than two - three days.
I cook then refrigerate. Next day I cut slabs into indiviual ribs. Place in aluminum pan, add a little apple juice or pineapple/orange, cover with foil and reheat.
You can also cut into half, third or quarter slabs...
Do a test and see what you think...
Roaring Fork BBQ :-D
Modified Traeger 075