by Jon Fila.
In my courses under Submission settings on the Assignment I set the Attempts reopened to Automatically until passed. Then I set the Maximum attempts to Unlimited. In the gradebook I click on categories and items and then the settings icon for that activity. There you can set the grade to pass, which I typically set at 100% of whatever points are allowed on that activity. That way students that don't get 100% on an attempt automatically have their submission re-opened for editing.
The only warning I have about this is that if your completion tracking for that assignment is to only be marked complete when a student receives a grade then the student will see a red X in their progress indicator.