Your custom audience will self-update automatically—you do not need to recreate it every 60 days.
Meta dynamically refreshes custom audiences like:
People who clicked on your ads,Visited your Facebook page, Engaged with posts or videos,based on the retention window you set (in your case, 60 days). This means it continuously includes new users who qualify and removes those who fall outside the timeframe.
So as long as your ad or page continues getting engagement, the audience will stay fresh and relevant without manual updates.