Forgetting the concept and world for a minute, you need to find the series engine, as RG said. What basic idea will generate stories week after week for several seasons? What you described -- the fugitive on the run and ticking clock -- are not story engines. They're plot devices.
Some examples to help out. On Game of Thrones, the story engine is the pursuit of the Iron Throne. On The Walking Dead, it's trying to survive the zombie apocalypse. On any procedural, it's finding the the murderer/criminal/whoever and bringing them to justice.
I think with yours it'll be along the lines of trying to save the last remnants of humanity before everyone dies off. You can see how that might play out from pilot to series finale.
Taking this a bit further, I've found Javier Grillo-Marxuach's concept of the operational theme to be very helpful...
I think once you figure out this part, you can come up with a story for the pilot that will ring true to the world and characters you've created, but will actually be different from your feature. You might have to just forget the feature altogether and start breaking a new story for the pilot. While you're doing that, you'll have an eye toward what might happen over the course of a season. Most likely 10-12 episodes in your case.
Whenever I write a pilot, I'm always mindful of how things will transpire over the first season, and when I'm done, I get to work on a bible that has anywhere from 3-5 seasons beat out. Some here might disagree with having that much, but the execs I've pitched like hearing at least the major beats and character arcs for how the series will play out over that long a span. Especially if it's serialized.
The thing to keep in mind is that you're creating storylines and character arcs that won't wrap up neatly at the end of the pilot, or even the first season. You want your audience to come back week after week, or to binge watch five eps in a night, so you're constantly having to keep things moving forward. It's very different from a feature, where your protag accomplishes a single goal and that's it.