Isaac Lane Miller shows up in the 1860 and 1870 census as living in Cincinnati, Appanoose County, Iowa. Exactly when he and Lucy moved back to Cleveland is unknown at this time. But we do know that Isaac died in Cleveland on November 18, 1879.  His obituary read:

The loss of Mr. Isaac L. Miller, brother-in-law of and bookkeeper for Mr. W. H. Doan, is severely felt. He died on Thursday at his residence on Doan street, aged sixty-one. For about thirty years, except 7 spent in Iowa he has resided in East Cleveland. He was a member of the Congregational Church, and much esteemed by his friends and neighbors.  Nov. 22, 1879.
Isaac Lane Miller and Lucy Ann Doan.