the correct answer (which germany will never land on) is to shoot the nazis. it has always been the only solution to a nazi infestation but germany has always found that difficult to swallow.
Shoot the nazis, establish a dictatorship of the proletariat, establish capital controls and develop the productive forces so the material conditions that lead to fascism don't come back.
A socialist government, or an organized proletariat and their vanguard party.
Unfortunately the decades of suppressing the left since the Cold War and annexation of the GDR means an organized proletariat and a vanguard party has not emerged in Germany (though there is the DKP), hence the rise of the far-right. A socialist government like the GDR would correctly label these as nazis and would not have let the far-right grow to this point.
How do you know innocent people would not get included in the "Nazi" categorization? In america lots of people get called nazi that have no relationship to it.