alyson,
All instructors have had this issue with their students. Since we are preparing the students for the career world, it is important that we provide them with opportunities to "curb" or limit their habits of procrastination. Unfortunately, the opportunities that instructors provide to their students have to come in the form of "tough love", in that receiving poor grades and suffering consequences will hopefully, force them to change the behavior. The key is for instructors to stick to their course policies/standards and provide periodic reminders to their students.
Tremayne Simpson