The great thing about hydraulic clutches is that they are maintenance free when running OK. Plus you don't need to adjust your clutch ever.
The bad thing is when they foul up it creates problems.
First things first:
Step one: Clean the sludge out of your clutch reservoir.
Step two: bleed your clutch until only clean fluid comes out the bleeder.
Step three: Get a cable clamp and clamp off your cable where it enters your clutch slave cylinder. something like this http://www.getprice.com.au/Stanley-Hose-Clamp-Small-Gpnc_500--54170237.htm
Step four: Remove the banjo bolt holding the cable to the slave cylinder then, remove the clutch slave cylinder. (3 or more bolts).
Step five: clean all the sludge and junk out of your slave cylinder. Check any seals for damage and serviceability. (replace seals/gaskets if required)
Also you might be able slide your clutch actuator rod out and check it for straightness and undue wear. Lightly oil it and put it back in.
Step six: Put it all back together, remove the clamp.
Step seven: Bleed your clutch again to refil your slave cylinder.
Your bike should now like it used to.
If however it doesn't, grap a hold of your hydraulic hose about a 1/3rd of the way down in one hand and work the clutch lever with the other. What your feeling for is the hose excessively pulsing in your hand. If it does that consider upgrading to stainless steel lines cheaper in the long run.
Otherwise it will be a side cover off job and check your clutch plates, friction plates for burn marks and your springs to see if they have compressed to much.