Sync Apps from Dev ➡️ Production - Sync Entire App
In this scenario the App already exists on the production environment and you made changes on dev. This scenario makes sense when you can fully reset the production environment to the same state as dev.
Warning
This will reset everything on production, including data and assets added by the editor.
Step 1: Re-Export Everything to File System
Note that the app is only complete if you also export the App-State in the Admin UI. Ideally you would export it together with all the content-assets (if there are any).

Step 2: Re-Sync with Git / Versioning
Typically you will have your App in git-versioning. So after saving the entire state, you will want to commit and push.
In the new location, go to the target folder. Then git-pull the repo.
Step 3: Re-Import / Reset App on Production
Now got to the App settings on the Production site and import everything.
Warning
Make sure you verify you're importing on the correct system. It's easy to accidentally be on the wrong system (dev instead of production).

🦸🏾♂️ If you want to sync the ADAM assets as well, you need the Patron feature AppSyncWithSiteFiles
History
- Export / Import of Apps introduced ca. 2sxc v4
- App-state export with content-assets 2sxc v15
- App-import from file system 2sxc v15