It is better when you've already x-ref'ed a drawing into another and you have to go back and change colors. AutoCAd does not recognise that you have changed colors.  Sometimes you can shut down your autoCAD after changing the colors in your x-ref'ed drawing, but this does not work to well.  The best thing to do is to find your xref'ed layers and change the colors there. Makes for your original to stay set-up the way you had it.  I do not know what version of CAd your using, but in 2008 when you x-ref a drawing it asks if you would like to reconcile your x-refed layers this is the good time to change any colors you need before reconciling them to your complete layer list.  I hope this helps.

If this is the problem, I think you simply detach the xref and reattach it. It must work. Only updating the xref is not sufficient lot of the times.

Regards.

Tom

www.indovance.com