Ellie-Mae Murphy, 13, was last seen in the Castlemaine Road area of the town at around 4.30pm on Saturday 11 September 2021 and officers are concerned for her welfare.
She was last seen wearing black ripped jeans, a white T-shirt, a denim jacket and black trainers.
Elli-Mae also has links to a number of locations in the south London area including Crystal Palace, West Norwood, Clapham, Tulse Hill and Streatham, as well as Kingston in Surrey.
Anyone who sees her or knows where she is should contact Kent Police on 101 quoting reference 11-1350.
