do i add a number to alumiconn connectors when using for repair work of aluminum wiring
Splicing devices don't have a box fill allowance, even though they may be chunky!

NEC 314.16(B) does not include wire-splicing or wire-connecting devices in its calculations; however, your concern is not misplaced, as the AlumiConn is indeed a chunky critter compared to a regular wirenut.  Fortunately, I doubt most folks will complain if you whack a surface raceway extension (starter) box onto the existing receptacle box to provide extra space, though.  If you have metal boxes, you can also use a standard single gang extension box or mud ring, but nonmetallic box extensions do not appear to be able to be stood off from the underlying wall surface, which is unfortunate when box volume is the reason for the extension.