The hazards of binary thinking and poor scope definition
There are two thinking issues here that impact innovation: the scope of the problem you define, and the range of thinking you allow. In this case, the team defined the scope of the problem as "replacing lost fees". That was the only scope, so the ideas were naturally focused around ways to generate new fees. The "range" of thinking and the potential options were limited by the scope, and by the very nature of the problem. This limited approach creates very little new thinking or interesting ideas.
My client and I pondered for a while, before one simple idea became crystal clear. The scope of the solution was so narrow that the only logical response that was "in scope" was "create new fees". What if, I said, we were to suggest to them that they try again, only this time change the scope of the problem. The only thing "out of scope" in the new brainstorm would be - wait for it - "create new fees". That would force the team to think differently and get out of its "paradigm". It would also remove the barrier of binary thinking, which looks like this: legislation reduced fees in one area of my business, so my response must be to increase fees in another area.
Far too frequently we find that our clients struggle to generate new ideas because their problem scope or problem definition is too narrow or too rigid. The scope then keeps the team cycling through the same issues and same ideas, and doesn't allow any new thinking or ideas. This is because there's often a knee-jerk reaction to replace like with like - remove a fee somewhere and I'll add one somewhere else. Instead, conduct several very rapid brainstorms where you shift the problem statement. Perhaps your first brainstorm should be in the context that you'd normally follow. Then, your next brainstorm should radically change the problem statement or expected outcome - what if "create new fees" was out of scope entirely? Perhaps a third problem statement or scope could be "if we could start from scratch, what would we do?"
Getting locked into one perspective and one way of thinking, one binary "This for That" approach is dangerous, since it appears we have exhausted a lot of options, when in reality we've only investigated a very few possibilities. This is why innovators talk about divergent and convergent thinking. It's a rare team that expands the scope and does the divergent thinking. Most simply leap to the convergent thinking as quickly as possible. And that's another reason so many ideas seem so humdrum.