There are two issues to consider; Engagement RPM and clutch slippage.
Engagement RPM is a factor of the weights in the CVT pushing out against the ramps as the CVT spins. The heavier the weights, the lower the engagement RPM, and vise-versa.
Clutch slippage is a different matter. If the clutch is slipping, the machine will move slowly at almost any RPM.
So, if the issue is the RPM at which the CVT engages, and the machine accelerates well with increased RPM after engagement, then the clutch is fine, and you just need to add some heavier weights if you want to lower the engagement RPM. Or leave it alone and live with it. What RPM is engagement at on your machine?
If the issue is that the vehicle is slow at high RPM or acceleration is inconsistent with engine RPM, then there are two things to consider. The first is the type of oil used in the engine. If the oil is not rated for a wet clutch, it can induce clutch slippage. Usually, this will correct itself with an oil change and a few hours of operation. The second, if the oil is rated for wet clutch use, is that the material on the clutch is either fouled or worn. Not likely with only 265 miles on the clock, but possible since you don't know how the machine was treated before you bought it. Being down 1/4 quart is not going to starve the clutch.
So, nail down the behavior as your first diagnostic, and then decide which tact to take.