Currently, there is no mechanism for calling ServerRestartPlayer in Blueprint.
There is also no mechanism for calling RestartPlayer in Blueprint that respects a GameMode’s CanRestartPlayer, unless you abuse StartFire via a console command.
It would be very nice if there was a way to trigger a PC’s ServerRestartPlayer RPC, or have alternative means of restarting a player in blueprint while respecting a GameMode’s CanRestartPlayer.