I honestly think that awareness would resolve the issue. The recent influx of new users don't really know what their best options are and choose to hoard SBD.
I recommend brightly highlighting (in wallet) the current %APR and the fact that SBD is intended go down around $1. An easily viewable conversion rate would further convince people to trade up.
Alternatively, I wonder what would happen if inactive accounts had their SBD suspended and removed from circulation until they logged in once again.