Yes, you have a couple options. The lever has a couple of friction discs with a big spring applying pressure that set the friction on the lever.
You can try and pray something like WD40 or similar around that area. This will help for a bit till it dries again.
From the rear of the tractor, if you follow the lever on the right all the way down, you'll see a big spring, two studs with a plate and nuts (nut + jam nut). Essentially you loosen the jam nut, then loosen the other nut in equal amounts between both studs. Try to keep it equal on both sides by counting the flats or turns. Move the lever back and forth to see if you like the feel. Adjust till you're happy. In the end, tighten the jam nut again.
The wrenches are 12mm if I remember correctly, could be 14mm but that's unlikely. You'll need two. One for the jam nut and the other to hold the other nut while you tighten the jam nut.
From factory, they tighten that spring all the way down for some reason, which makes for a stiff lever. Plus it's a short lever, which makes it worse. On mine, I added an extension and helped a lot.