You can make your own offline backup file in the settings section of your project, to reach the project setting click the cog icon next to the project name.
Click the backup button and a file with a complete project content is generated.
You can now create a new project based on this file. to do this, click the arrow in the "create new project" button and select "create new from backup".
This will create an exact copy of the project you backed up with a new name.