Resetting your Review Cards in Mango not only completely resets them to zero, it also allows you to get new Review Cards from previously completed lessons. So, it's like starting the course over from scratch.
Here is how to Reset your Review Cards (if you have Review Cards at all):
1. On the Learning Pathway, click on "Start" in the Daily Review box.
2. Click on "Edit" to edit the number of cards.
3. Click "Reset" to reset your Review Cards to zero.