this may sound dumb but the sure way to ck the clutch is warm it up till bike loses power, come to a dead stop and put it in like 3rd gear, rev it up and dump the clutch, if it goes nowhere or barely the clutch is the issue. If the bike dies, prob not the clutch. If indeed it is lean do NOT run it till problem is solved.
PS check for the simple things like the gas cap vent.