Automatically Redirect Students back to a Failed test

Hi! I hope you are doing well today. I have been trying to figure out this problem for a while now.

Right now, I have pre-tests at the beginning of each unit. These pre-tests are mandatory, but the answers to the questions do not have to be right in order for the student to move forward.
At the end of each unit I have chapter tests. These tests are also mandatory; however, this time the student is required to get 100% on all questions in order to proceed to the next unit.
Now, where I am having an issue is that when someone finishes a test or pre-test for that matter, it doesn't redirect them back to the test or pre-test page to show the student which answers he/she got wrong or right....because of this my students do not realize they are supposed to retake the test.
I have been getting many emails from my students questioning me on why they cannot proceed to the next unit. Of course, this is because they did not get a passing grade on the unit chapter test, but they have no way of realizing this, because it did not redirect them back to that page upon finishing their 1st attempt.
So, in summary... How can I make sure they know they need to retake the test? Is it possible to redirect them back to the test they failed? Also, is there a way to reset the test answers completely so they can take the test from the beginning? Is there any other suggestions you have, or another work around that I am not seeing?

Thank you for all your much needed input in advance.