Hi @vesal,
Simply make a new submission (this time including your PDF in the ZIP file) with the same approach, and it will overwrite the previous submission to that approach. Only the latest submission to each approach counts.
If you have another method, then the solution is to submit it under a different approach (you’re allowed up to 3). Rather than select an existing approach on the submission form, create a new approach by entering a different approach name (and fill in all the other information). Each of your different approaches shows up independently on the leaderboard (so you have a chance to evaluate them all).
Let me know if you have any other questions.