It really depends on what your personal situation is at the moment. If, once you've been promoted to your new league, you have a team that can compete in the playoffs, don't hesitate to raise ticket prices on your bleacher and LT seats by a few dollars; it'd be good to initially aim for a ratio that is roughly 70% bleachers, 25% lower tier, and the rest court-side seats, then take the results you get from the first few home games to plan out further modifications (if any).
But if you aren't at that level of competition yet, you may have to settle for lowering your ticket prices for a bit. Look to improve your squad, and give the fans a reason to come to home games. Invest in training up your young players, if you have any. However you feel is the best way, if you keep it up and spend the money wisely, eventually you'll get to the point where butts start filling the seats again; at that point, experiment with the pricing. If you raise ticket sales and people are still showing, THAT is the right time to consider an arena upgrade.
So basically, take things as they come, and go from there with how you want to do things.