Sounds like you have the TPO roofing material (thermo plastic), not the EPDM roofing material which is a rubber based material. Jayco used the TPO material for a couple of years on some HTT & TT models, than went back to all EPDM.
Anyway, I had the same TPO material on my '05' Eagle and found it to be a more robust material than the EPDM material (replaced my TPO with EPDM a couple of years ago). I'm not aware of any kind of "repellent" for the TPO material, don't know if one would really protect against leaks.
I never even wash my TT roof (TPO or EPDM), I just rinse it off once in awhile. Keep in mind that the 23B has a relatively flat roof compared to most HTT's, TT's etc., so I would avoid walking on it other than checking vent caulking, roof seams, etc.. If you do wash it I would do it from a sturdy step ladder along side the 23B.
Also, when not in use keep the 23B a little nose up so that water can't pool on the roof, and will then run off the back rather than over the front angled slide panel.
Detailed description of TPO per Alpha Systems, Inc.: "TPO – Thermal Poly Olefin – was introduced to the RV and Marine Industries in 1994. It is resistant to algae, mold, fungus, and other biological agents. The chemistry of TPO allows for no chalk residue or degradation of the membrane through its useful life. The TPO membranes are non-skid when wet and therefore are used frequently as floor covering in the pontoon boat industry as well. The chemical additives used in TPO for protection from UV light are not self-sacrificing. Instead, they operate in a regenerative fashion as they interfere with the degradation reactions that occur from UV light exposure. Some features of TPO are the advanced polymer technology, weight reduction and easy installation due to its soft and pliable nature. TPO carriers a 12 year manufacturers’ warranty."
Alpha Systems, Inc: http://www.alphasystemsinc.com/Home
Hope this helps a little.