Other than the diplomatic debacle of Germany attempting to tempt Mexico to engage in a hopeless war with the US if America and Germany went to war which led to the Zimmerman Telegram, Imperial Germany had no plans to invade the US, having more than it could handle in Europe and the Middle East. However, plans had been drawn up to invade the US from 1897 to 1903 at the request of the Kaiser who was perturbed at the growing global influence of the US.
The first plan written by a German naval Lieutenant envisaged a naval war of the east coast of the US with raids against American east coast naval bases.
After American victory in the Spanish-American War, the plan was revised to include German troop landings and occupation of Boston and New York.
A third and final plan concentrated on bringing America to the negotiating table by seizing Puerto Rico and establishing a naval base there and polished up the ideas of invading at Boston and New York. The plan noted that none of this could be undertaken unless Germany enjoyed peace in Europe.
The plans were shelved in 1906.
The late author Robert Conroy, who specialized in alternate history novels, published 1901 in 1995 which posited an Imperial German invasion of the US at Boston and New York as outlined in the German invasion plans.