The box on the handlebar is a reservoir, extra fluid, a safety measure. It's the fluid in the piston and line that makes the clutch work. It's being down that far may point to a problem in the system, but shouldn't make it hard to clutch. Probably air or moisture in the fluid. A change sould take care of your problems.
Change brake and clutch fluid every year or two.
Fred.
Fred, the piston to push the fluid to release the clutch is in the reservoir,,,being low on fluid, he may be trying to squeeze air (which will compress) instead of fluid (which doesn't) therefore,,,dragging clutch.