The ornamental design for a refillbottle, as shown and described.
FIG. 1 is a side perspective view of a refill bottle showing my new design;
FIG. 2 is a front view of the refill bottle thereof;
FIG. 3 is a side view of the refill bottle thereof;
FIG. 4 is a side cross-section of FIG. 3;
FIG. 5 is a top view of the refill bottle thereof; and,
FIG. 6 is a buttom view the refill bottle thereof.
The broken lines in the drawings showing the raised letters on the bottle shoulder illustrate the portions of the refill bottle that form no part of the claimed design. The lines showing a break in the sidewall of the refill bottle in FIGS. 1-4 and space between those break lines form no part of the claimed design.