I would mostly agree with you here. I am in this situation myself having won 2 promotions in 2 seasons. I now find myself the weakest team in the league. The one thing I don't quite agree is lowering ticket prices.
For the original poster's situation, his arena is only roughly 5000 seats. Increasing prices to maximize revenue would be a much better plan than to cut prices due to low fan ratings in a tougher competition. Being in a higher division also increase your fan base/support to counter the negative effect of constantly losing games. This would have saved him some cash from doing a lot of arena expanding in one go which he can use to get a better player to help him compete.
With that said a combination of expanding arena and raising prices is the way to go to take advantage of the high fan base. He can still play around with the ticketing prices once his arena finishes building and can gather if he is filling it out or not.