Right now I got a problem, my clutch has started to slip over 4000rpm with 3rd and 4th gear

Well what makes it so big problem? Let me explain.. The clutch I use now have been balanced as a same "package" with crankshaft, flywheel and cam pulley. Well, as you may guess the balance gonna go atleast wrong when change a new one, which I have to do, if I´m going to drive anymore in this summer. I propably need to ask more info from the machinery shop guy who did the balancing job, that how bad is this clutch change for my engine
When I get to garage today, I´ll take exhaust, and driveshaft away, so the gearbox will faster to pull backwards, as soon as the clutch parts arrive