I've noticed particularly going up from 3rd->4th->5th the revs dont seem or sound like they are dropping as much as they did
That actually sounds like a problem with the engine management! You seem to be stating that the revs are "holding on" between gearchanges, rather than dropping much quicker.
Hurdy is correct with his simple test on clutch slip. Another test, and you'll need to find a quiet flat straight road, is to do as Hurdy suggested, but whilst keeping the accelerator to the boards, GENTALLY press the clutch pedal. If the engine revs rise frantically the moment you merely sneeze at the clutch pedal, then your clutch is shagged. If you need to press the clutch pedal roughly half way to the floor, then your clutch is fine!