I have done maintenance on my 2012 roof last May.
I cleaned it with a mild soap (Spic-N-Span) and water mixture and a soft scrub brush.
I looked at the edges of the existing sealer to the fiberglass roof for separation, dried out, and usually dark dirt stains where water puddled.
Then I purchased 4 tubes of self leveling sealer and applied over all the existing sealer edges and fiberglass roof. I didn't find any dried out edges so just laying a thin later over the existing did it for me.
Hope this helps you.
2012 Georgetown XL - 378TS 49,000 miles
(2013 - 98 days) (2014 - 117 days) (2015 - 67 days) (2016 - 115 days)
USAF Retired - MSgt