Contact them, explain what SFI is about, refer them to the SFI Basics and the Launchpad. Tell them about your experiences in the hope that they will be inspired to continue.
Other than doing those things, that's all you can do.
People are either going to be motivated to continue on, or they will just move on to something else. Don't feel bad or frustrated if that should happen. Wish them the best of luck, then continue working with the affiliates who remain.
