If you use this extension : http://branch.qlik.com/#/project/56728f52d1e497241ae698c7
You can backup your apps into json files and merge theese in an editor.
If you create an empty app with the appropriate data connections you can restore the merged json file into the empty app, execute a "Load data" and you are up running.
Can you please explain how to backup apps into json files and then how to merge the json files in editor? I am very new and don't know how to perform this step with json files.