Based on the recommendations of others (including the factory VP from Haartz, our cars' top fabric's manufacturer) I've used both the cleaner and restorer "RaggTop" products, which produced great results. Looks good as (better than?) new.
I do agree with Ad about the question of whether you need to do anything to the top - if the water still beads and there's nothing stuck to it, leave it alone. Once I scrubbed the top, the only way to get it back to beading was to go through the whole deal or retreating it with the RaggTop protectant.
BTW, if you go with the RaggTop, mask off the paint and glass to prevent a lot of extra work. The can says that overspray wipes right off, but I had a bear of a time getting it off myself. The stuff was tenacious (great for the top protection but a pain if you want it off the car's surface
)