My husband has arranged to have flowers delivered to the restaurant before, and the staff have them waiting at our table when we arrive.
Does it have to be dinner? What about arranging to do something as opposed to dinner - ice skating at Olympic Plaza and bring along some fancy hot chocolate in a thermos, to share? How about a wine/whiskey/bourbon tasting? S'mores and hot chocolate around a campfire? Does she have any specific hobbies or interests that you could work a date around? For example, if she was dog crazy, what about a lazy evening stroll with her dog, if she owned one, and a stop at a pet store to buy some new toy or dog sweater for her mutt? Things like that.
It doesn't always have to be dinner.