For one silicon cannot stick to silicon. If you must reseal you must remove. The Dicor type sealant for roof seams is a self leveling with means it will flow better into the cracks of the seams. You could also add more to the Dicor if needed without removing it.
From an online article:
'If you see a water leak in your RV’s rubber roof don’t make the mistake of trying to repair it yourself by using a silicone sealer.
In our RV Service department the most frequent issue we see with incorrect caulk, is the application of silicone seal.
Installing silicone seal is absolutely the WRONG WAY to caulk anything on the roof of an RV.
Why not use silicone?
Over time silicone tends to shrink and pull away, once it has pulled away, water can go right under the silicone and get trapped. Water trapped underneath the silicone can never dry out.
Removing silicone seal without doing additional damage to the roofing material is nearly impossible.
As a general rule the caulking that should be used for an RV roof is not available in a big box or hardware store.
If you are going to repair a leak yourself we recommend the RV caulking be purchased from a qualified RV supply store to ensure you get the correct product for your RV."