What do you see as the top one or two or three reasons for the decline and weak culture? First step is to identify the problem.
That's really the key. Probably the easiest best way to find out the reason for the decline as to ask the members. Send an email blast to every family who played during the last year and ask then to fill out a survey, which you can set up for free at surveymonkey.com. Ask questions about the coaching, the facities, practice times, game schedules, etc. Ask what they like, and what they do not like. They won't be shy about telling you, especially those who are not happy. If you learn that your facilities or your coaching or your league politics or whatever are turning people off, then you know what you need to work on. If competition with travel is the issue, then try to find ways to coexist with it.
But it could be that your issues are more structural or demographic in nature. You may need to look at county census numbers to get an idea of what's going on. For example, if the number of families with young children is trending down, there's not much you can do but be more proactive in attracting the pool of players you already have, by advertising tryouts, doing PR, and trying to make the product more attractive. This is where getting your high school coaches and players to run free clinics can pay off. Similarly, if the issue is that you've got a lot of non-baseball playing immigrant families, you'll need to do some outreach so that the kids learn what's so great about playing baseball.