I create a SharePoint-hosted app but when this app is redeploy then Data should be Lost.
For avoiding to lose exist data in SharePoint Add-ins (SharePoint-hosted) there is two way to do that :
If you did a modification just in your scripts or css you can use SPFastDeploy
I prefere you to use this way is to map Network drive with your App web Follow this link replace master page path with your App Web path.
Note : If you modify list or content type or site column or Workflow so you need to redeploy.