The app reloads every time when I switch back to it from some other application on iPhone. That's a common behaviour/problem with Safari on iPhone. The app also doesn't work offline.
Cache the Resources:
You can try to add a simple cache manifest-file to the app, i.e. use the HTML5 Application Cache to make the app work offline. This should also stop it from reloading.
PS. NirvanaHQ uses this technique.
Cache the Application Data:
To make the app work offline, you will probably also need to store the application data in the browser's local storage.