You can find BitLocker Password Recovery tool on Windows Server 2008 R2 under Features. You can install the tool by opening Server Manager and under »Add Features« look for »Remote Server Administration Tools« »Feature Administration Tools«. Here select »BitLocker Diver Encryption Administration Utilities« and follow the wizard.

Once install process completes you can open Active Directory Users and Computers and right click on domain level. You should now see »Find BitLocker Recovery Password…«