If I leave my surplus funds in the same bank account to use for the next election, can I still file my final C-4 for this election?

When you settle your financial affairs after the election, file one last C-4 report for that election campaign, then leave the money in the campaign bank account.

When you begin the next campaign, file a new C-1 candidate registration or a new C-1pc political committee registration for a ballot measure committee. Create a new ORCA campaign for that election and begin filing C-3 and C-4 reports for the new campaign