Depends. The material covered in Safe Zone trainings evolves over time — at least, it should. If you’re doing a Safe Zone where the material hasn’t been updated in years, it’s at best out of date, at worst harmfully inaccurate). And tons of folks do trainings using the “Safe Zone” moniker that include very different activities and learning outcomes.
It’s not required (at least not by us, because we aren’t requirers/certifiers/overseers — we’re just a free online resource), but with that in mind, it never hurts to get a refresher, if you can. And don’t let the fact that you haven’t gotten a refresher prevent you from doing what you can to advance the goals of Safe Zone in your workplace: mark yourself as an advocate, speak up and interrupt bias, and do what you can to make your space more inclusive of LGBTQ+ folks.