Make a catalog of all your dolls and their stuff and/or pack them up in storage bins or something for a little while.
I didn't pay attention to how many Power Team Elites I had until I was weighing them in pounds. With the Monsters it was a change in face molds that stopped me. With Barbies they have to have X amount of joints. No ball jointed dolls bigger than my Obitsu 60 (except the special prize twins). There's always exceptions but giving yourself some ground rules no matter how arbitrary can work.