Upvote:3
I had the same situation about one year ago. I had a layover in ORD for my trip from LHR to CUN and I had a valid ESTA. I just modified the application with the new flights information and 'TRANSIT' in the US address.
Upvote:9
The last rule refers to the yes and no boxes you have to tick, e.g. did you ever get deported. The transit checkbox is not part of the yes/no boxes. In fact, you don't even need to update the application at all while your esta is valid.
So if nothing changed except the fact that you are there for a transit, then no, you don't need to apply again.
The checkboxes: