The former Newcastle United striker joined the club in the summer of 2023.
The powerful German-born frontman made his name in non-league football, showing prolific form in front of goal for Barking before making the move to Newcastle United.
Since joining the Inver Reds, Westendorf made his European debut in the Champions League coming off the bench in the First Qualifying Round against HJK Helsinki.
The striker has since joined fellow Sports Direct Premiership side Ballymena United on loan until January in order to get more regular game time.