The ornamental design for the combined pom pom and helmet replica holdertherefor, as shown and described.
FIG. 1 is a perspective view of the combined pom pom and helmet replica holder therefor showing a first embodiment of my new design simulating a basketball;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof, the left side view being a mirror image of the right side;