The Duolingo redesign has make to harder to test out to a higher level. It seems I can only test out to level 1. Why? I am an intermediate Spanish speaker.
Presuming you are using the website, after testing out to level 1 as far as you can go using the tree/course shortcuts:
Click on any individual skill you wish to test out further in, a little box should pop up with various icons on. One of these icons is a key symbol. Click on this to test out to the next level.
If you are not using the website, I cannot speak for the availability of this feature.