Your app should follow the client-server model -- that is, your app is a client that downloads new updates from your server on a regular basis. Your client-side code would consist of the user interface and code that uses XMLHttpRequest (AJAX) to communicate with your back-end in order to download additional content. I don't know what CMS you're using, but I know WordPress has an API that you could use to download blog posts and the like.
That said, you can also employ hot code pushes. See CodePush for one service that enables this. I offer this solely for completeness sake, but I don't think this would be the best option in your case (IMO).