What about changing the target? They have been targetting families since the beginning, Sunday afternoon games, kids days out, Nixie etc. Has it worked? Not that I can see.
In general families are likely to have less disposable income and a Nix game is a bit to shell out for, also less likely to come if the weather is a bit off. So why not see if a change of target might work, go for the students/young workers/professionals who might have a bit more disposable income won't be so fickle weatherwise? Just a thought.