The ornamental design for a reversiblelampholder, substantially as shown and described.
FIG. 1 is a top perspective view of a reversible lampholder showing our new design, wherein the darker solid lines indicate structural features thereof and lighter lines are used to indicate contour;
FIG. 2 is a top plan view of our new design;
FIG. 3 is a front plan view of our new design;
FIG. 4 is a bottom plan view of our new design;
FIG. 5 is a rear plan view of our new design; and,
FIG. 6 is a left side plan view of our new design, the right side being a mirror image thereto.