Updating your apps to Windows 8.1 Preview provides significant benefits.
· Numerous performance improvements in common scenarios, including app startup time and panning within large data collections
· Improved rendering of animations
· New and improved controls
· More flexible app layouts and Window states
· Additional tile sizes and templates
· Better integration of contacts and calendar
· More natural in-app search experience
Updating your app now will help give you a chance to prepare for some of the changes and new features in 8.1.
Important: The Windows Store is not yet open for submission of Windows 8.1 apps. Windows Store apps written for Windows 8.1 will be eligible for submission to the Windows Store later this year. At that time you will be able to onboard new apps or onboard an 8.1 version to the same app ID as your existing Windows 8 app. This enables your 8 and 8.1 apps to share ratings and reviews – it also means that users will automatically get the 8.1 version of your app when they update and you will be able to continue to update both your 8 and 8.1 versions moving forward.
To help developers get started on updating their Windows 8 apps to Windows 8.1 the following white paper has been produced http://go.microsoft.com/fwlink/?LinkID=304117