You should disassemble & repack if the grease purges out the front (Bearing Buddies), but it depends on the hub. The grease routing needs to purge the old stuff completely out. Bearing Buddies don't do this. Dexter EZ-Lube hubs do; the old grease purges out thru a hole in the center of the spindle. I have a '93 Floe Pro 100+ with Dexter EZ Lube axle. I shoot 'em with the grease gun in the spring, plus before, in middle, & at return of a trip to the Rockies. I check bearing preload & spin the wheels by hand each spring. Never had 'em apart. No problems.
BTW, the wiring & lights have never been touched. I grease the pins & socket on a dummy connector & stick it in the trailer connector when parked to preserve the contacts. I built a wooden hood that covers the hitch end when parked. Hose it down after every use to get the salt off. Spray WD-40 on the coupler & lug nuts. My Floe gets good care, but has exceeded my expectations. I am lucky.