I think it is a good thing that you are patiently leading the way letting them know that they must meet your expectations.  It takes a lot for a teacher to continue regrading an assignment, but some of your students will actually learn from your efforts.  It's funny to hear adults talk about some of the things teachers made them do when they were in school and how much they learned from it.  It's all about the learning, and I think you are doing a great job.