I bought a 2003 last September, but my lever needs to be around half way out before it engages. I told the Harley dealership and they pretty much told me that's a characteristic of the bike and there's nothing you can do about it...after a year, I've just gotten used to it. I don't know if a slipper clutch will make a difference or not and I've never heard of the button mod that ElrodontheV-Rod suggested.
My suggestion is to go to your local Harley dealership and ask them if it needs to be replaced or if that's just the characteristic of your wife's bike (if it is, you can ask if a slipper clutch will work better?). If not, on the bright side your wife won't have to pull the lever all the way in to shift it! Anyways, good luck!