As most know, if "My Living Doll" hasn't been thrown up against powerhouse NBC Western "Bonanza," it probably would've been renewed for another season or two. Probably the other factor that caused CBS to pull the robot's plug was what to do for a co-star. By mutual consent, Bob Cummings had turned out to be a liability, but nobody was sure Jack Mullaney was the replacement. He wasn't a star name, and only had a few episodes to prove himself. Instead of starting a new season with Jack, or adding someone else, CBS had plenty of other sitcoms ready and waiting.
Check Julie's interview about the show in FILMFAX #135.