What method does she use to remember other things (the date that the new movie is coming out, when she and her friends are getting their nails done, etc)? Figure out what kind of learner she is. Is she a visual, an audio, or a touch learner? Does she remember a date when she hears it, or does she write this stuff down somewhere, or does she set out a tangible reminder of some sort?
That method, if it works (if she never forgets that her friend wanted to borrow a dress on a certain night, if she never forgets that she's supposed to be at the mall at 7 pm on Friday) should be the way she remembers school work.
I suggest that you tell her that now that she's almost able to drive, and almost old enough to have more freedom, that you will no longer, as of X date (like a week from now) not remind her about homework. But tie it in to privileges that she wants. If her work isn't done well and on time, there's no way she's getting her license or having permission to use the car. There's no way she'll be permitted to have a smart phone any more (assuming you're paying for her phone). There's no way you'll drive her to friends' homes or to parties and give her a curfew and more freedom. And it's not only about the grades. It's about being responsible, proving herself capable of managing the details of her life (and right now, school is her priority whether she intends to go to college or not). It's about showing that she's reliable and able to manage details. So, she can assume personal responsibility for her school work, or you will continue to manage every aspect of her life, including not allowing her to drive, not allowing her to go out and return home by a curfew, not having a phone with internet access. Her choice. And you've got to follow through. You can show interest after the fact ("how did the test go today, dear" instead of "don't forget you have a test on Tuesday").