It is definitely harder to get a new job if you already have tenure than if you don't.
Getting a tenure track position is hard enough. Getting a tenure track position under geographic constraints is really hard. You should be as flexible about the job itself as well as its location as possible.
If you're willing to sit tight for a few years, I would advise building as wide a network of professional friends and acquaintances as possible by giving talks at conferences, department seminars and colloquiua. Keep an ear out for job openings for which you are particularly well suited and in departments where you know your candidacy would be supported. You have to be extremely realistic and objective about which schools and departments will be willing to hire you. It will help a lot, if you know people who are willing to help you look and give you frank advice.
Get a teaching letter and apply for jobs only when you are really ready to leave. You don't want to do this more than once, if you can help it. But also be ready to do it more than once, if you don't get any or any sufficiently attractive offers the first time.
It is indeed a difficult time to do this, so I wish you all the best with this.
ADDED:
Be a good citizen in your current department in the sense that you should fulfill all of your teaching and service responsibilities as well as possible. You need as much good will as you can get from everybody including where you are now.
If you have any particular talents or skills (outside the usual research credentials) that a math department might find valuable, try to develop them but without undermining your core credentials. One way or another, you want to try to find some way to make yourself stand out relative to everybody else looking for a job.