The first thing you must ask yourself is why she stopped doing or turning in her work. If she doesn't know how to do the work then the answer is simple: help her with the work.
Another reason she may have quit is that the work is too boring, or irrelevant. If this is the case, discuss with her teacher ways the instruction can be differentiated to create a challenge.
A third common answer is that the child is in the midst of a power struggle, either with their teacher, a sibling, or you. If this is the case you must offer her choices, incentives and consequences that will empower her.
Whether the problem is academic, interest or power, creating a personalized system for doing homework will help. Give your child some boundaries to work within such as a specific amount of time, and consequences for not completing the tasks, but allow her to choose the particulars.
It is easy for a parent to get so caught up in their child's accomplishments that they don't want to see her fail. However, to have pride in her own work she has to do it. Check her work when she asks, praise her when it is good, but don't do the work for her.
You do not necessarily have to pay for grades, or come up with expensive items or flashy vacations to get school work done. However, there should be some kind of incentive system in place to balance the consequences. Encouraging words go a long way for day-to-day tasks. More choices, such as picking the restaurant when you were going out anyway, or a few days off from a chore she hates, should suffice for bigger jobs. She needs to know that there are rewards for her good work.
When your daughter is working on homework, do some homework yourself to show her correlations between school and adults work. At least, keep the TV turned off and save other "fun" activities for later, so she doesn't feel like she is missing out on something while working.
Sometimes the work gets overwhelming, and she will need a break. Don't be so rigid that you create stress in the interest of keeping a schedule. Obviously, this can't happen every day, or the breaks becomes routine. Know your child and their frustration level, so you can keep her from crossing it.