Chosen Solution

If I replace my motherboard, will I have to reprogram the IMEI and Serial Number?

that depends on the motherboard. if you get one specifically designed for replacing motherboards, then it will come with no serials installed, and you will have to use certified applications to reprogram the board. if you get a reclaimed board from an already activated device, it is just a quick swap. (There is a possibility that these reclaimed boards could be blacklisted or damaged if purchased from a disreputable source.)