I've had the same problem! Since Lost ended I haven't been truly excited about any new TV. However, I've been watching The Walking Dead and, *finally*, I've begun to experience that sensation of disappointment when it's almost over and the adrenaline of "What happens next?!" and emotion for the characters - all in the way Lost gave me. The show is very suspenseful, has continuity, questions, cliffhangers, survival, and character focus.
Also, though I haven't seen it yet, Once Upon a Time was created by Lost writers so it should be given a try by any Lost fan, I'm sure.