It would be a good idea to renew it before it expires, so you could renew it for 1 year by passing any specialist (CCTA, CCTE, etc) exam or for 2 years by passing the full-blown CCSE exam. Once your CCSE expires your only path to renew is the full-blown CCSE exam. There used to be a "CCSE Update" exam that you could pass to renew/extend your CCSE cert but that exam has been retired. See here: sk163417: Check Point Learning & Training FAQ
Attend my online "Be your Own TAC: Part Deux" CheckMates event
March 27th with sessions for both the EMEA and Americas time zones