How long has this been going on? Alot of people get into a lazy slump but it's only temporary. Like when all you want to do is watch tv and NOTHING ELSE. Then when you finally watch a crap-ton of tv, youre like.. hmm I think Ill go grocery shopping, dishes etc.
My bf knows I like him shaved. He grew his out. I told him while he was showering that i preferred him clean and he told me he knew, but didn't shave. A week or so later he wanted me to give him head, which I did for a minute than gave up telling him I didn't want to cuz the hair and he said ok, and I continued by hand. He still didn't shave.
I said nothing more, because obviously he knows where I stand, no sense beating a dead horse. And a few weeks later he's shaved! YAY! I noticed right away and rewarded him. He said he was being lazy and it was a little irritating. The ordeal for me what about a month worth of bushiness, which isn't bad at all.
Your girl could be in a lazy slump where everything feels like.. "fk it!" And she'll eventually snap out of it. Or maybe shes decided she really hates shaving and never wants to do it, but she knows how you prefer it so she'd probably end up doing it eventually just for you, you just have to be patient. I know if my bf preferred bush (even though I despise it) that I would definitely let loose sometimes, if not all the time, to please him.
You said she knows your preference, if you keep re-iterating that to her, you'll just be a jackass. Hopefully you're more compatible in other aspects of your relationship.