I have a twenty year gap when I "lose" an ancestor. The only things I am certain of are that I cannot find him and that he moved during the period between 1850 and 1870. One approach that might be helpful is to learn about historical events that were going on during this time period and what have cause him to move. Were new territories opening up during this time? Did the Civil War impact his life?
Think about those "gaps" you have in your ancestor's life? Then get beyond your ancestor and ask yourself "what was going on outside my ancestor's life during this time period that might have caused him to move?"