The ornamental design for a lapboard for a wheelchair, as shown and described.
FIG. 1 is a front perspective view of a lapboard for a Wheelchair showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right side elevational view with the left side being a mirror image thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom view thereof.
The broken line showing of the human figure and a wheelchair in FIG. 1 is included for the purpose of illustrating environment and forms no part of the claimed design. The broken line showing of screw type members in FIGS. 1, 5 and 6 represent environmental structure and form no part of the claim.