The first thing is don't ignore the fees or stop paying altogether because you can't afford the full increase. That is just going to get you in hot water with little defense. So where do you start?
First, if you are not going to be able to make the increased payment but can make the prior payments, talk to the association and tell them you are going to keep paying at the old rate until you can work something out on the increase. They are likely to look more favorably on an owner who is trying and making regular payments versus an owner who just stops paying in protest.
Second, start looking at whether the association followed the proper procedures to raise the fee. Condo declarations and bylaws frequently have procedures that must be followed to raise fees, and not all associations follow the procedures as well as they should. If you find that the procedures were not followed as stated, you may have a way to challenge the increase. How to do so would, however, require you to talk to an attorney who deals with associations to help walk through what can be a procedural mine field if you decide to raise a challenge.
Third, talk to some of the neighbors, particularly those that were up to date on their fees before the increase. There may be enough of you to take action jointly under your association documents, but that option is governed by state law and the specific documents that govern your community. An experienced community association attorney can help you with the analysis and work with you on your options.
This answer is for general purposes only, and it does not create an attorney-client relationship.