There are entire books written about developing a referral system to get people to give you more referrals. There are specific things you need to do, such as ask for them, track them, and reward people for giving them to reinforce the behavior.
I think one of the strongest and most lasting way to get more referrals is to give them. I guarantee you that if you go to your next leads club meeting and have a quality referral for every person there, you will be the most popular kid in town. Keep this up for a few weeks and you'll get back as many if not more than you give.
This would be an intense task. You'd feel like all you did was give away business. But I think this is one of those slow-growing techniques that would go exponential. You couldn't keep it up forever, maybe? But if you did this every few months, you'd create a lot of momentum that would keep the business rolling in.