The ornamental design for a bottlecap with fan, as shown and described.
FIG. 1 is a first perspective view of the bottle cap with fan showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a second perspective view thereof.
The broken lines depict portions of the bottle cap with fan that form no part of the claimed design. The dot dash dot broken line is an unclaimed feature line that serves as a boundary to the claim. The broken lines below the dot dash dot broken line illustrating a bottle is environment that forms no part of the claimed design.