How do you tell if its Dicor.
Lots of other roof sealant brands have been used on RVs.
I would follow your roof membrane manufacturers recommendations on using any product up there.
I remove loose sealant and use self leveling Dicor and make it like OEM. Others use similar products.
For hairline cracks in the sealant I do as Wyo says and just add a small layer over it.
Keep in mind when adding a lap sealant you don't want to make a dam up there for water to sit in.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides