The ornamental design for a lockextensiondevice, as shown and described.
FIG 1 is a front elevation view of a lock extension device showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a rear elevation view thereof; and,
FIG. 7 is a top perspective view thereof.
The use of separation break lines and brackets in the drawings indicate that the precise length of the device is not claimed. The appearance of any portion of the article between the break lines forms no part of the claimed design.