Updating a hackintoshed OS X virtual machine, or a real hackintosh for that matter, is a bad idea. While you can update a mac VM that you're running on a real mac (which is how I tested developer previews of Mavericks without touching my mountain lion setup). Hackintosh installers are first modified by another program so they will execute on Non-Apple hardware, and after that you still need to manually install the required kernel extensions to support all of your hardware. SO, just running the Mavericks setup from the mac app store won't work. Either get unibeast and modify the installer so it boots, which will probably not boot after the install due to outdated kexts, or look for a new VM that already has mavericks, I'm sure they exist.
<Insert passage from "The Book Of Chrome" here>