The problem is you've updated to the new 64bit Traktor and there are only 32bit ASIO drivers available for the DJM-2000. Until the 64bit drivers are released, you need to use the 32bit version of Traktor:
Go to "C:\Program Files\Native Instruments\Traktor 2”. In this folder you will find the current 64-bit version of TRAKTOR PRO called “Traktor.exe”. Please rename this to “Traktor64.exe” so that you have a backup of this version.
Open the “x86” subfolder. You will find another “Traktor.exe” inside. This is the 32-bit version of TRAKTOR PRO. Please move or copy this application up one sub-folder to the "C:\Program Files\Native Instruments\Traktor 2” folder.
Now launch this newly copied “Traktor.exe” - this will now be the 32-bit version of TRAKTOR PRO.
You should now see the DJM-2000 ASIO available to configure your output routing.