Many things can lead to lack of water beading.... first, the product may have simply worn away and you need to reapply a new coat. second, there may be something on the paint that has lowered the surface tension of the sealant and therefore killed the beading.
Water beading/sheeting is simply a result of high surface tension. Many products (like some shampoos, solvents, etc) contain surfactants which ultimately lower the surface tension and therefore effect the hydrophobic properties. If you happened to use a high concentration of shampoo, that is the most common cause of early life lack of beading.
If you live in an environment with a lot of pollen/dust this time of year like I do, a buildup will accumulate on the car and that will negatively effect beading/sheeting, however it should come back somewhat after a wash or two.
Keep in mind, lack of beading/sheeting doesn't necessarily prove that your sealant has failed or is completely gone, it just proves that the surface tension may have been altered. The easiest way to restore beading is to simply add another layer of sealant, or simply use a quick detailer with hydrophobic properties after each wash.
Meguiar's D156 is a spray detailer that contains synthetic polymers which enhance slickness, gloss, and water beading. It is effortless to use, and very cost effective.
If you want absolutely crazy water beading,
Sonax Brilliant Shine Detailer gives some amazing results in the hydrophobic department
This product is not slick feeling, but it is easy to use and really excels with impressive beads.
As for the clear bra, it can certainly polished. You should also decontaminate it (clay bar) and protect it (sealant) as if it were painted. These products can be treated just like clear coat, however they are generally quite soft and do not require nearly as aggressive of an approach when correcting.
Clear bra with weird holograms/buffer trails from the dealership.
Removed with M205 on a white pad using the PC7424XP.
Hope that helps!
Let me know if you've got any more questions.
Zach McGovern
Detailed Image Ask-A-Pro Blog Author
www.AttentiontoDetailingPeoria.com