This wasn't discussed any further in the show as broadcast. The actor was written out at the insistence of the studio after it became apparent that she was facing an ongoing civil lawsuit and that the optics of having a "reaper" who'd actually taken a life (a few years before, she'd managed to narrowly avoid jailtime on a manslaughter charge after hitting and killing a child on a crossing) was something they weren't keen to have on a show that was already underperforming. Showrunner Bryan Fuller evidently had plans for her return (see below) but those never made it to air as he left at the end of season one and the second season showrunner had no interest in continuing the plotline. Her character was simply replaced with a near-identical actress who could fulfill most of the plot requirements without the need to rewrite more than a few superficial pieces of dialogue.
So what plans did Fuller have for her?
Apparently she was to return from the afterlife and lead George on a special voyage of discovery, leading to a plan to storm the afterlife and demand some answers from the powers-that-be. Unfortunately the whole thing failed to materialise.
It was also my first show so I was fighting for everything. I didn't pick or choose my battles, everything I believed in I fought for, including cast members I believed in, like that whole Rebecca Gayheart debacle.
Her leaving the show was because the studio executives had second thoughts because here is this woman who accidentally killed a child in her past and is now playing a Grim Reaper. They got uncomfortable with that and told me to let her go. She's great on the show and everyone thinks she's great on the show and everyone likes her as a person. I went to the mat for it and it got really ugly. It was only one of the battles that got really ugly.
I was going to bring Rebecca Gayheart's character back at the beginning of season 2 and have her fall out of the sky and send her and George on this mission. Here's a grim reaper who returns from the afterlife and has something to say about it, and the question would become how the characters could "storm the castle" and come back.
But those episodes were not meant to be.
Comicbookresources.com - REFLECTIONS: TALKING WITH BRYAN FULLER