The ornamental design for a cupholderinsert, as shown and described.
FIG. 1 is a top perspective view of the cup holder insert design;
FIG. 2 is a bottom perspective view of the cup holder insert design;
FIG. 3 is a front view of the cup holder insert design;
FIG. 4 is a rear view of the cup holder insert design;
FIG. 5 is a left side view of the cup holder insert design;
FIG. 6 is a right side view of the cup holder insert design;
FIG. 7 is a top view of the cup holder insert design; and,
FIG. 8 is a bottom view of the cup holder insert design.
The dashed broken lines showing an engagement aperture, a flexible lip, and a top surface of a bottom of the cup holder depict portions of the article and boundaries thereof and form no part of the claimed design.
The dash dot broken lines showing inner sidewall surface diameter variations depict portions of the article and boundaries thereof and form no part of the claimed design.
The cup holder insert is shown with a symbolic break in its length and width. The appearance of any portion of the article between the break lines forms no part of the claimed design.