The ornamental design for a heated seatpad, as shown and described.
FIG. 1 is a perspective view including a top, one side, and one end of a heated seat pad according to the new design;
FIG. 2 is a perspective view including a back, an opposite side, and an opposite end of the heated seat pad;
FIG. 3 is a planar view of the top of the heated seat pad;
FIG. 4 is a planar view of the one end of the heated seat pad;
FIG. 5 is a planar view of the opposite end of the heated seat pad;
FIG. 6 is a planar view of the back of the heated seat pad;
FIG. 7 is a planar view of the one side of the heated seat pad; and,
FIG. 8 is a planar view of the opposite side of the heated seat pad.
The short dash broken lines represent stitching. The dash-dot broken lines shown in the drawings are directed to environment and are for illustrative purposes only and form no part of the claimed design.