I know this is 2 years old, but I would also like this option. I am a teacher and we had our students take this diagnostic quiz their freshmen year, and now they would like to take it again as juniors to get more updated recommendations for the test. I hope this becomes a feature soon!

I agree with johnsons, I would like to reset my diagnostics. If it is possible, please bring back Practice test 2 and 4, perhaps with a disclaimer of the concern!

Hello!

Thank you for your questions and concerns about this topic. Although it is not possible to reset a diagnostic test, Khan Academy will gradually adapt the content level and recommendations according to your performance as you continue to work on your activities.

This means that the recommendations are not fixed and are not always traced back to your diagnostics performance. Once you start working with the recommendations set by the diagnostics, they will gradually change as your level improve.

I hope this helps but please let me know if you need any further assistance!