When you install Vivado on Windows machines, it is possible to select file association of .XPR and .DCP files for Vivado in Windows Explorer.
Is it possible to fix this file association or set it after installation?
Setting up or repairing file association after the original installation is not supported by the Vivado installer.
However, there is a workaround:
Launch the network Setup installer (C:\Xilinx\.xinstall\Vivado_2014.1\networkShortcutSetup.exe)
In the product selection tree, unselect all of the checked installation options (Leaving them selected will do no harm but is unnecessary)
In the destination panel deselect the program group shortcut creation (Create program group entries), but keep the desktop shortcuts and the Create file associations.
Complete the installation process.