How can I upgrade to a higher level?
You don't need to take a test to progress. You simply need to continue through the skills, as they unlock. (If they have failed to unlock, make sure you've done all the lessons in all the skills on the line you are currently on.)
The progress quiz has nothing to do with your ability to continue through the tree. It tests you on the entire content of the tree, thereby giving you a baseline against which to measure the results of future tests.