I would upgrade honestly. I had a 2016 Cannondale Trail 7 and 29r and I was in the same spot. Upgrade or buy new. The amount of changes with frames and gear from 4 years ago, it wouldn’t make sense to upgrade. You would spend 500ish to get a better fork, drive train, wheels, brakes. I would just get a new bike. Just my thoughts though, do what you would like, you’re spending your money not mine. lol