Developers can get the update view the Mac App Store or by signing into the Mac Dev Center at the link below.
Developers should be warned that Apple says you cannot update from the developer preview to the final release.
OS X Mavericks Developer Preview 2 is pre-release software. Do not use this pre- release software in a commercial operating environment or with important data. You should back up all of your data before installing this software and regularly back up data while using the software. You will not be able to upgrade from the OS X Mavericks Developer Preview to the final release.
Read More [via Mac]