BOSS RETRY
What you need to do is at the boss Initialize event right after the Alive variable, set IsAttacking to FALSE
Make an event dispatcher call it “Retrying”
Then in your level blueprint, take the boss reference node and BIND EVENT TO RETRYING, place it right before the DoOnce
Drag a wire from the red box and type Custom Event
Hook that custom event the Reset of the DoOnce
In your Boss BP, check the retry even and after setting boss location set IsAttacking to TRUE and CALL RETRYING (drag the retrying event dispatcher in the blueprint and select CALL)
What this does is when the menu retry button is pressed it fires an event in the boss that will relocate him and make his blueprint believe that he is attacking so he can’t move or do any actions. Then it resets the trigger box and when you overlap it again, it will re-initialize the boss and tell his blueprint that he is no longer attacking and he can perform regularly now.
I hope that helps 
