A new "Buffy the Vampire Slayer" series could be a sequel to the original series following the comic books produced by Dark Horse Comics, which picks up after the destruction of Sunnydale at the end of Season 7. The canonical comic series sticks to the television model with Season 8 through Season 12. Obviously, the cast would be played by new, young actors, but this reboot could continue Buffy, Willow, Xander, Dawn, Faith, and the new slayers' story after the original series ended.
Season 8 begins one year after the destruction of Sunnydale, with Buffy acting as general to her army of slayers, as she did off-camera in the last season of "Angel." In the Season 8 comics, the world finally learns vampires and slayers are real. The battles become epic and the slayer network goes worldwide. With numerous comics in each season, there's plenty of source material to build a multi-season reboot of "Buffy." There's even source material for spin-offs following Faith, Spike, and Angel.
Conversely, a new television series could follow the comics released by Boom! Studios after the license to "Buffy" was taken from Dark Horse after the Disney-Fox merger. A series based on the Boom! Studios comics would be a true reboot, taking the Scoobies back to Sunnydale High, but in contemporary times. This would allow a new series to explore the horrors of adolescence in our technologically advanced and socially connected times.