Answer
You may want to re-cache the .MSI, if you have a small fix (such as a change to a registry key), but you do not wish to distribute a new patch or upgrade for the product. The most common reason for re-caching an .MSI is to fix a mistake in an already installed .MSI. The /fv command-line option for msiexec.exe (the Windows Installer service) runs the install from the original source and re-caches the .MSI on the local computer without requiring redistribution of the .MSI file. Note that transforms cannot be re-cached, and cannot be applied when re-caching an .MSI.
Related Links
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/msi/setup/command_line_options.asp