How we loose xp?
@MISAmisha, why earn xps at the first place, if later one has to find ways to loose those . @Ahri fox once told me that she is 'gold for life' may be she can help you because she has managed that since ....
By losing challenges, unlocking lessons by spending XP, having a Best Answer mark removed, resetting your entire lesson progress, etc.
If you send too many run requests for your buggy program which will cause their server to burn and rot. They might penalize you 100 XP for every run requests before fixing your code. Moral : Fix your code or get it fixed to save you precious XPs
By gambling them at Las Vegas! Whatever happens there stays there :(