This is an interesting move: a soft reboot for a show being done in for the second season. To fix what are presumably problems that worry the studio and/or the executive producers, season two of The Leftovers is going to have a new location and a lot of new cast members, basically keeping the premise and starting over somewhere else.
According to Deadline, HBO's post-"Rapture-like" even show will ditch the fictional Mapleton, New York location in season 2. We don't know yet if that means we'll get a similar town with a different fictional name (a real attempt to just do-over the season) or if they'll maybe move the action to a city with a recognizable name.
Of the cast, the members staying on full-time are Justin Theroux and the actors playing his family: Amy Brenneman as his estranged wife, Margaret Qualley as their daughter, Chris Zylka as their son, and Carrie Coon as the love interest. Basically, it sounds the Garveys and their issues are moving to a new town to start over. Although, also rumored to be staying is Christopher Eccleston as former reverend Matt Jamison, which doesn't fit the mold quite as well.
Deadline also says that Liv Tyler and Ann Dowd could stay on, with other season one cast members guest-starring during the season. Which allows the show to not pretend that season one didn't happen, but lets them extricate themselves from any baggage they may not want from it.
Picking up and moving the show from season to season is an interesting tactic. It's similar to what Helix is doing — its first season was pretty much confined to a research facility in the Arctic. Season 2 is starting with a whole new disease and new locations, with the characters being the constant.
In some ways, it makes sense as a tactic for a show on the bubble, which wants to complete a story in a single season, in case that's all they've got, and still make it possible to do another without being a full-on anthology like American Horror Story. And for The Leftovers, it's a way to reboot even with a season already done. Normally, you'd re-do a pilot if things are going badly, but The Leftovers' problems weren't in the pilot.
Should be interesting to try to figure out what survived the move and what was left behind when season 2 of The Leftovers starts, though.