Don't expect to get an upgrade on LH unless you pay the fare difference, or use certificates/vouchers (and you are already in an eligible booking class) or you are in one of the highest booking classes and the flight is full in your class of travel. I'm afraid they will not upgrade you because there is no aisle seat left in Economy.

However, they do keep some seats back for families and people who need them for whatever reason. Make sure you have access to your reservation on lufthansa.com and try online check-in 23 hours before departure. Alternatively I suggest you go to the airport early (if possible) and explain that you would like an aisle seat and see if they can assign you one.