Skipping levels in Duolingo after you've already done the test that places you in the level it thinks you should go is quite easy. With three steps and a bit of skill in the language you're learning (or some cheating) you can increase the difficulty of Duolingo to an absurd level.
Step 1: Scroll down the tree and click "Jump Here?"
Step 2: Click "Let's Go"
Step 3: Complete the test correctly.