Not yet. But it's easy to update your app. All you have to do is hit 'Sync' within your app and your data will update. AppSheet apps are designed for offline access with only occasional synchronization over the network. As it is now, we do not update your app automatically-- updating your app automatically would use up much of your device's data and battery. However this feature is in the works.
You CAN however, have your app update automatically upon Save of new data. This will happen automatically if you have not disabled it in the Editor. You can learn more about automatic updates here.
You can disable automatic sync by enabling Delayed Sync. You can specify this feature in the Basic Editor>Settings tab and the Advanced Editor>Settings>Security tab. Please be aware that choosing the Delayed Sync option is a Premium feature, because it is assumed you or your users will be working offline.