I too have been a victim of married sex, and I know how it is. Not a lack of caring, just...habitual.
Things that have worked for me:
1. Do something New. Drag him into a changing room, or look up a new position, or do some new fantasy -- something that solidly breaks the mold. I would suggest a little more than just a new nightie or porn video, though. Think pushing limits, like, you know, you used to do...way back when?
2. Sometimes sex is habit because, well, it's always THERE. It's so available, that you stop worrying about getting enough, and thus stop getting much at all. I don't why, but it happens. Best response is to clam up for a while; harder as a sub, I know, but still do-able: bet him he can't go without sex for the next two weeks; I suspect you'll both find it on your minds a lot more, and after two weeks you'll have crazy sweaty sex. You'll appreciate what you have a lot more, because you were concious of not having it.
Good luck, and remember that talking logically about having sex doesn't help as much as jumping him on the dining room table. It sounds, though, like the problem is more normal married people issues than bdsm specific.