Grandfather the current occupants. Set a 20 year term with the possibility of renomination for ten years. The lower court judges are seriously drunk on their power. Set a ten year term, possibility of a second term. Or just give them a retention vote every ten years
It would take a constitutional amendment. Fat chance.
a much easier way than changing the constitution would simple be to impeach them after a set period of time or a certain age. The congress already has the right to impeach them for any reason.