You tend to get more JV participation when girls are allowed to participate in both club and junior varsity. Some coaches tell the girls they can't miss hs practice, others tell them not to come on days they have club practice. Finding what works is key to building up the individual player...which eventually translates into team success.
What really helps the program out and allows for junior varsity wins to translate over to varsity wins is quality coaching and low turnover rates. Give the team a coach who knows what he is doing and more girls and parents will feel comfortable coming out. When you know a coach and can trust him over the years with all of your young ones, even better.