If you want to backup a project, one option is to publish the project. By doing so, even if the data on your local device is deleted, the project will be stored on the server side, allowing you to import it. You can also synchronize it when working on another device.
For information on how to publish and import projects, please refer to the following:
Publishing a Project - Link
How to Import a Project - Link
However, if you cannot publish the project, the repository is what holds information about projects and other data. You can backup everything in bulk by periodically compressing it into a Zip file and saving it to cloud storage.
The following may be helpful as a reference for repository retention: