Why not offer to "buy" the business from those who are fleeing. A few of my coaching clients are employing this are having fantastic results by asking those folks who are leaving the industry the question - "Do you want to sell your Business?"
It works like this, you ask the FL (Fleeing Licensee) to send a hand-off letter to their sphere of influence who they have been working for the last couple of years. The letter explains how their friend is going back to their previous career, but they have found a real estate professional who will give them amazing service and that you are the recommended choice for their future real estate needs. You then absorb them into your "VIP" SOI program and continue the warm relationship. As the transactions come in, you will offer to pay a referral fee for the first year to the referring licensee, the second year it is ½ of the first year's fee and the third it is ½ of the prior year's fee. You have created a win-win for both your business as well as given some value to those jumping out of the business.