When Update 1 (or, just Update as Microsoft calls it) released in April 2014, many IT Pros took wait-and-see stance. Update 1 was to provide fixes and new features and with any changes like this, it's completely logical to wait. And, one of the most important reasons to hold-off from deploying any update en masse is to make sure that it can be managed. Since Update 1 brought so many new features to Windows 8.1, particularly to the desktop side of Windows, without the ability to configure the features centrally, a deployment could turn disastrous.
I know many IT folks have been waiting for the updated Administrative Templates for Update 1 to ensure a smooth rollout. So, just three months after the release of Update 1 the GPO settings are available.
Unfortunately, the Group Policy Settings Reference for Update 1 is not available yet, so we'll have to wait a bit longer for that, it seems. The Settings Reference is a handy Excel spreadsheet that can be used to search and locate specific GPOs settings to plan configuration. That most current version was released in January of this year, so it doesn't provide the latest information for Update 1.
Download the Administrative Templates here: Administrative Templates (.admx) for Windows 8.1 Update and Windows Server 2012 R2 Update