I’m not familiar with GitLab, but with GitHub it should be as simple as committing the changes and force pushing to the remote repository (make sure you make a copy of the uncommitted directory in case of any unexpected failures):
$ git push <remotename> <branchname> --force
ex.
$ git push origin main --force
Without force pushing, git will ask you to rebase to the remote version, which is what you don’t want.
If this does not work, worst case scenario you can still create a new GitLab server and push files there, which is probably not a desirable solution.