Did you search in the QMC (Qlik Management Console)?
If you open it, one of the 6 main things you see in the middle of your screen is "Tasks" (the one in the top left corner). If you read the description underneath it, you will see "Tasks are used to reload data in an app...".
Tasks can also be found as the 6th item in the menu on the left-hand side of the screen. Click on that and create a (reload) task for the app you want to schedule a reload for. That should do the trick.