There is no Solution for Recovering the Corrupted App in Qlik sense, But you can Recover the Script Code of the Corrupted App ,just follow the Below Steps,
-->Check for the same name in the C:\ProgramData\Qlik\Sense\Log\Script folder
-->By Doing This you'll get the Code of an App.
-->But the Visualizations have to be rebuilt again.
***Tip:Daily take Backup of your app.
Thanks & Regards,