How to Repair Microsoft Dynamics CRM Server 2013 once the update rollup or service pack is installed?

Hello,

I am going through the following Technet article:

Repair Microsoft Dynamics CRM Server 2013 ( https://technet.microsoft.com/en-us/library/hh699749(v=crm.6).aspx )

The repair option asks for the original CRM DVD media location. The problem is that how the repair procedure knows about the service packs or update rollup files location?

My concern is that the repair procedure replaced the update DLLs (or other files installed by CRM service pack installer) by the RTM files in the original setup DVD.

Is there any special consideration for repairing Microsoft Dynamics CRM Server 2013 once the Service Pack or Update Rollup is installed?

Thank you,