Status "Complete" means that the user has entered values for Infrastructure, Services and Business Arrangement. If one of the 3 categories have not been completed (i.e. never been saved), then the status will stay as "in Progress". However, it is not necessary that all the values in a particular category needs to be answered fully in order to reach the status "Complete".
Just click on the actual percentage values in the table grid in the Audit History page to continue entering the values for each category.
Select the category you want to record and click on "Save as Audit" button. It will then prompt with a message to save all information as "Save as New Audit" or "Overwrite existing Audit". Click on "Existing Audit" and choose the Audit to overwrite or to add a category to an existing Audit.