The ornamental design for a deflectorplate, as shown and described.
FIG. 1 is a left side rear view of invention;
FIG. 2 is a Right Side rear view;
FIG. 3 is a Right Side top view; and,
FIG. 4 is a Left Side top view.
The broken line showing of portions of the deflector plate is included for the purpose of illustrating environment and forms no part of the claimed design.