I have just been asking this same question! I have had a 9 motif grey mop (Modern) Alhambra necklace for a few years -- for those who aren't familiar with the design I've attached a picture below.
I never wore it because I am really more comfortable in the longer necklaces (18 inches of less makes me feel claustrophobic

). When I saw the grey mop (Modern) Alhambra on the website recently I figured they had brought it back. I tried to order another one (to attach to my necklace) through NM three weeks ago and they told me that it is absolutely retired and cannot be ordered.
There is a happy ending to my story though.

A sweet tpfer told me that Beladora had one and I was able to order it through them. The nice thing about attaching two (Modern) Alhambra necklaces together is the clasps are hidden so it it virtually impossible to tell that it isn't one necklace.