Well that's a strange thing,I also promoted to Div II,this season,and did not notice any drop in my fans so far .
I have won just 3 games,mainly because  training my players is more important to me  then winning games.
Just  want to stay in 2  ,and thats no problem for me,and next seaon Iam  gonna do a lot better,I hope.:)
I did  a large expanding (almost 3000)  on my arena,and  it's  not  sold out  ,but my fans still support me ,pretty good.
I fear the all star break a bit though,but Iam  still in the Cup,and  maybe that's the reason my fans  keep coming to my arena.