J.R.R. Tolkien’s early sequel project for The Hobbit was called The New Hobbit.
After The Hobbit became a success, George Allen & Unwin asked Tolkien for another book about hobbits. Tolkien began work in 1937 and initially treated the project as a continuation of the earlier children’s story. The manuscript soon expanded into a far more ambitious narrative involving the One Ring, the history of Sauron, and the fate of Middle-earth.
The project’s working direction changed substantially as Tolkien developed the mythology and narrative. The finished work was published as The Lord of the Rings, not as The New Hobbit. The early title is therefore a useful glimpse into the book’s origin, but it is not an alternate published title. Tolkien’s extensive revisions also explain why the final novel is much darker and broader than The Hobbit.