The ornamental design for a cleaningsponge, as shown and described.
FIG. 1 is a perspective view of the new design for a cleaning sponge;
FIG. 2 is a top view thereof, the bottom view being a mirror image thereof;
FIG. 3 is a left side view thereof, the right side view being a mirror image thereof; and,
FIG. 4 is a rear view thereof, the front view being a mirror image thereof.
The broken lines in the drawings are shown for illustrative purposes only and form no part of the claimed design. In addition, the surface shading illustrated in the drawings is provided merely to highlight the contour of design; it is not intended to be illustrative of texture or gloss.