With the Eurowings flight also still running, to some extent Lufthansa are competing with themselves to destinations within Germany and to some European destinations. They even depart within around 2 hours of each other.
I've just done my bit for the route though and booked a return from Berlin at Easter, for a similar price I paid for my Eurowings flight at Christmas.
About 15 rows are already fully reserved on the seat selector for the return, with 4 rows of Business Class.