I just flushed my clutch fluid. I hadn't done it and the bike has 25k on it. Don't know if the PO had ever done it, either. It was black. The lever is easier and smoother to pull now. I never imagined it would make that much difference.
As far as replacing the clutch, chances are it isn't needed. Usually a slipping clutch is caused by the clutch spring, part # 4NK-16334-00-00, getting weak, not bad clutch plates. The spring is around $60.00 and easy to replace. You can also upgrade to the Barnett Clutch Spring Conversion Kit, part # 511-90-10002 for around $125.00.