Installing the new release
As per the initial developer preview announcement, there are no upgrade options between developer previews. As such, our recommended course of action is a fresh install (in a new directory) or a re-installation (in the existing directory). If you are doing a reinstallation in this manner, you should pay attention to our specific reinstallation guidelines.
Note that if you are running Developer Preview 4, you can likely get away with a master data rebuild rather than a reinstall.