As far as I know you can’t. I use a game instance to keep permanent values, which again - AFAIK - is the only (or at least best) way to have one blueprint persistent throughout your game.
You set your game instance class in ‘edit - project settings - maps and modes - game instance’. Keep an eye out for this pulldown to reset itself, it’ll do that if you rename your active game instance BP for instance and causes crashes if so on my end at least.