Have you tried calling Klipsch at (800) KLI-PSCH ? That's (800) 554-7724.
I somewhat doubt they would have an upgraded crossover, but sometimes they surprise me. That said, most of the Klipsch crossovers are not complex and have relatively few components. So, as long as you can read the component values and can solder, it shouldn't be too large a project to replace a few parts. Coils/inductors are usually not marked for value, so that presents more of a challenge to upgrade. If you had an LCR meter, you can measure the originals. But typically, capacitors are more where the manufacturers really cheap-out on crossovers, and coils are more risky to change, because any good designer will have included the DC resistance of the coil in the crossover design. If you upgrade to heavier duty coils, you will almost certainly be changing the DCR, something you don't worry about with capacitors. Anyhow... !
Best bet is to search around the forums where Klipsch people reside and see what is recommended. Good places to get high quality capacitors include Madisound Speaker Components, Parts Express, Solen, MCM Electronics, etc. !