Send frequent team mails or individual email to them by referring to genealogy.
Use chat facility provided by SFI
Use a2a friend to get connected
Give rewards and incentives to those are semi active.
Continue to get connected to Movers
Refer them to read SFI news and Forum on the updated news on SFI
However, even these methods are used, it depends total on the interest and initiative of the downline members the desire to earn money from SFI.