Mine broke on my 2008 at 17,000 miles. The mechanic has a 2006 ZX-6R Ninja and his broke at the lever too. The ferrule with its chrome sleeve is hard to extract from the lever, but if you set the adjuster at 5 you'll be able to get it out. I have the official shop manual and this is not mentioned. We should probably lube them every 2 years but you should know that this job takes a good hour after you remove the front tank and back rear covers, extract the old cable, lube the new one, and position it through its 3 wire loops.
My experience w/ my two Vs and a bud's KLR, is that Kawasaki sets up the clutch so that it's VERY hard on cables. IF the 'release-point' of your clutch is FAR from the handlebars, then when you pull the clutch lever to the bars (waiting for a traffic light, etc), you are REALLY stretching the cable, asking for it to fail.
I set mine (and others) up so that INSTEAD of about an inch of thread showing on the adjuster (by the lever), only about 3 to 4 threads show (1/4"). This way the release point is when the lever is about 1.5 to 2" away from the grip, so you're NOT stretching the heck out of it, waiting for the traffic light.
How exactly are you lubing your cable??
Joseph - you didn't ask me, but I reduce pressure at the lever adjuster by turning it till NO threads show, align the 'slots' and pull the cable out. Then I put WD40 into a small pill bottle, then using the plastic tube that comes w/ a can of WD40 (tho' I use bulk WD myself) I dip it into the container, cover the end w/ my finger (holding about 1" of WD40) and slowly release it into the end of the cable, moving the inner back-and-forth. Probably takes me 10 minutes total.
...and works like a damn!