Sajjad,

the first thing I come to think of is to copy the process XML source from your test environment to your production environment. This is straightforward, if the two only differ in the changes that you made to the CR item type. Otherwise, you need to diff and merge the changes from your test env process source into you prod env process source.

After having updated the process in your prod environment, you may want to synch all existing CR items to the new changes.

Cheers
Timo

Working directly with configuration source is risky and generally is not recommended.  Accidentally you could induce an incomplete change and corrupt the project area in the repository.

Process Sharing is a better approach.  Set the Project Areas to form a Master (Providing) and Child (Inheriting, contains users).  The actual project area where users are members of is a child project area.  The Parent is providing the process. 

When there is a need to refine the process, create a new master and switch to inheriting from the new master.

As we are talking about a Production instance, I would recommend taking a complete application and database backup before attempting the approaches.  Once you are convinced that the changes are flowing in consistently, you could incorporate that as a process.  Each time you bring in a refined process, ensure you take a backup.

hope this helps.