I'm a little late on posting to this thread but I had the dreaded floppy clutch lever. For me it was when I was cruising down the highway, not using the clutch at all, but sometimes after stop and go. I'd reach for it after a bit and there would be nothing there. After bleeding it a number of times the traditional way with the same problem recurring, I went to the Kawi dealer to ask them. The tech there said he'd seen the problem a number of times and the only way he fixed it was to replace the clutch line. Since my bike had 70k miles he said that was probably my cure. I installed a new clutch line and rebuilt the master cylinder. Bled the clutch both traditionally and with a vacuum device. I rode for a couple of months with no issues. Ahhh, victory! Nope. 4th of july weekend I got stuck in stop and go traffic on a 90F+ day and suddenly I only had half a clutch lever. I managed to coast down the road with the clutch pulled in, only cycling it occasionally. After a few miles the clutch came back, almost like the air or whatever found it's way up to the reservoir. It's been fine ever since, about 5-6k miles.
In the meantime, I've bought a sst line for both the brakes and clutch. I've replaced the brake lines but not the clutch yet. I'm waiting until I don't have any rides scheduled for quite awhile. I will also rebuild the slave cylinder at that time.
I have to add that I think the Kawi clutch line is one of the stupidest designs I've ever seen. It transitions from rubber to steel a number of times for no real apparent reason. I think all those transitions are places for air to get trapped. I'm not sure where the air comes from, at least in my case, since the bike had been working fine and I do periodic fluid changes on both the brakes and clutch system.
This has been the only real problem I've had with the bike for 78k miles so I am very happy but also perplexed about this phenomenon.