Maybe a rotating judicial review board (like Senate seats but yearly) of randomly picked judges and others with law knowledge. Upon receiving a complaint, a random subset of the panel would be picked which could could censure any judge at any time for any obviously activist decision, but with no actual punishment. Any judge censured by three different panels (meaning those from the first censure panel are at best a minority) could be kicked out.
It would take three years to remove a judge, but it would keep the judiciary free from political reprisal for decisions as it's supposed to be.