Because Kickstarter isn’t always an option.
The Veronica Mars movie looks like it's happening thanks to fan persistence and an incredible influx of financial support. But there's more than one way to bring a dead TV show back to life.
Comic Books
Buffy the Vampire Slayer ended its television run with Season 7, but Season 8 continued the story — provided fans were willing to switch mediums. Buffy wasn't new to comics, but Season 8 was unique in that it was canon: Joss Whedon's stamp of approval assured that whatever happened to the characters in the comics actually happened. (Read: a lot of death.) Though perhaps not as satisfying as watching an eighth season would be, the comics were a great way to continue the story on a much, much lower budget.
Dark Horse
Netflix
Diehard Arrested Development fans never gave up hope that the series would return, however unlikely that seemed. And look, now that long overdue wish is coming true! The idea that Netflix can bring classic shows back is an exciting one, although few series would inspire the same enthusiasm that Arrested Development and Veronica Mars have. Netflix also encourages binge-watching, which is ideal for these cult series, most of which people discovered by marathoning episodes long after the shows had been canceled.
FOX
New Network
For shows like Damages and Friday Night Lights, the wait wasn't even very long. Both series looked like they were done for until DIRECTV snatched them up. In addition to permitting more bad language and gratuitous nudity, the network switch allowed DIRECTV to establish itself as a sanctuary for fallen shows. And yes, they could totally spice things up with a liberal sprinkling of f-words. Honestly, it's strange to think of a time when Damages had to censor itself. I'm pretty sure Patty Hewes was born cursing like a sailor.
DIRECTV