No need to "re-caulk" unless you see cracks in the caulk thats down now. We have a 2012 FR Lexington with the fiberglass roof, and I'm up on the roof at least once a month for routine checks. Original caulking is still in great shape. You will notice a change when it goes from being pliable to hardening, and thats when you'll start seeing cracking.
Just do routine checks of anything that comes up through the roof, vents, antenna and wire, fridge vent, and the rails that run where the roof meets the sides. Also, check the joints where the front and rear caps (if you have them) meet the roof.
I give mine a good cleaning a few times a year, using a mix of a good auto wash and some Krud Kutter and water. I just use a good soft bristle brush and rinse. Do not wax it unless you want to play slip-n-slide off the roof.
I and probably a lot here use Dicor caulk. Two types, self leveling and non sag. Use self leveling on the roof, non sag for vertical surfaces. If you need to re-caulk an area, use some mineral spirits to clean the old caulk surface and surronding area, than a bit of acetone to remove any residue. You want to have a clean surface to apply the new caulk to.
Also, never, ever, use a silicon caulk on the rig. It dosen't seal well, and nothing else will stick to it, even new caulk. Onlu use stuff that's made and developed for rv use.