You would need to edit your document in an app that supports that document format. Then on the web interface you can go to the Repertoire > Documents page, click Edit, and re-upload the file. Or from an Android device, you can replace the file in the application data directory and go to Repertoire > Documents, select the document name, and reselect the file. Or from an iOS device, you can "open in" or import the file and go to Repertoire > Documents, select the document name, and reselect the file.