When creating or editing an assignment that has a Submission Type of File Submission, you can limit the number of attempts by checking the box labeled Allow a limited number of submission attempts, under the section Submission Options.
Once this box is checked, a new input box will appear labeled Maximum Attempts that will allow you to enter how many times you want students to be able to try your assignment.
Also be aware that if you check the box, but do not enter anything for Maximum Attempts, Notebowl will assume that you are not limiting the number of attempts. The Allow a limited number of submission attempts option will become unchecked when you save the assignment.
Students will be notified that an assignment has a limited number of attempts, as shown in the image below:
Students will also be informed if they no longer have any attempts remaining:
But if you decide that your students need another chance, you can always increase the maximum number of attempts, even after submissions have already happened.