I am in the same boat like you're. Xp is really hard to move even with 100 units daily ahead with challenges only. Here we have to show our creativity. Codes - interesting ones. Helping others questions and win badges eventually. Badges can be taken once, but can scores multiple times when the criteria is met. New language challenges are good source for a while but after time it became again harder. Required more time, exploring the exams of the challenges and so on.
There can be more badges for quizzes.
1. Get 20 quizzes approved in each language
2. Get 200 quizzes approved in the quiz factory
3. Get 100 quizzes approved in a language
4. Get 20 quizzes approved in at least 3 languages