We're not seeing multiple dead versions of his body anywhere, and he retained the items he collected along the way--the only one shown as a notification when he revived was the cloak. So, from the perspective of someone standing at the spawn point, does it look like he just got up that last time already at high level? This implies that time is reset with each new respawn. That means that the timer on his sister's arrival would also reset. He could then keep grinding until max level, regardless of how long it took, since he could just commit unalive once he maxed out, and start one last time with the maximum amount of time still left to save his sister.