Although the owner's manual doesn't mention it, that's normally what the little pin just outboard of the clamp does. Duh, I can't remember what that part is called but it's like a little threaded rod with an Allen head (2.5 mm??). Can't hurt to try it, just count the turns, and if it doesn't do what you want, take it back to its original position.

Picture here (Flash, so I don't know how to embed it)

You may need to readjust your brake cable after adjusting the lever position.