Motorcycle Repair: Clutch slips on acceleration, clutch slips, clutch discs

Question
I own a 1995 Honda Shadow VT1100C2 ACE.
I purchased it used, and had work done to it when I got it.
New tires, Battery, Fork Seals, and had the spline shaft and shift lever replaced.
They also did an oil and filter change, using Amsoil.
Lately I have noticed that at highway speeds, if I roll the throttle down a little hard, (i.e.: passing ) the engine seems to rev up. If I let up a little it goes back to a more normal RPM. The bike shifts well most times, and I have no other issues.
How can I correct this?

Answer
Mike, The problem is that the clutch is slipping. The oil is a good oil as I sell it also. A couple of things to look at If its a cable type then it needs adjusted with a little free play at the handle. The worst case is that the clutch discs and springs need replaced as they arent holding the fiber discs tight allowing them to slip and glaze up.There are 9 fiber discs and 8 metal discs that can warp due to the slippage. Check to see if you have about 1-2 mm gap between the perch and the lever when you start to squeeze it before you feel any resistance from the clutch cable.