ZIPP 303 no more breaking surface

I have ZIPP wheels that I bought back in 2000 something in St croix half, from a guy that worked with ZIPP. I used them rearly, but more often now, since I broke ksirium back wheel on one of my falls. I raced a couple of long marathons 200km+, during really bad weather, rain… Now I see that even that when I bought new carbon brake pads there is not so much braking surface on the rim, so the grip is really bad. Almost zero in rain. Is there and solution to this problem, is it possible to put something on the rim to get the brake grip back or do you guys know something to save my favourite wheels. Besides that I did not replace any spokes and had no problems with wheels even if they are 7 years old at least.

Please help me out
thanks

I can not belive that noone experienced the same problem with breaking surface on the carbon rims and carbon brake pads.
Again pads are new and wheels have like 3000 k ± 10% all together.
Any solutions??
thanks