^Yes, that's the specific 6M$M/TBW remake I'm thinking of. I don't know of any others.
And building stories around stock FX/action footage was a common TV practice. It happened several times on The Incredible Hulk
. "Never Give a Trucker an Even Break" was built around footage from Steven Spielberg's debut TV movie Duel
, and "Earthquakes Happen" was built around footage from Earthquake
. Galactica 1980
also repurposed FX footage from Earthquake
as a computer simulation of a Cylon attack on Earth.
I recently saw an early '50s B-movie called The Magnetic Monster
whose climactic action was mostly a reuse of footage from a 1934 German film.
Several Lost In Space B/W episodes were redone in color.
I'm pretty familiar with LiS's production background and I'm not aware of any such instances. The color seasons of the show were radically different in tone and approach than the black-and-white first season, much campier and much more focused on Dr. Smith and the Robot, who was a much more human and comical character in seasons 2-3 than he was in season 1. Any first-season script would've had to be heavily rewritten to work in a later season.
Maybe what you're thinking of is the original ship-crash footage from the pilot, which was filmed on color stock so that it could be reused if the show later went to color -- and which was indeed reused in color in the early second season. Or maybe you're thinking of how Land of the Giants
' "Wild Journey" was basically a rehash of LiS's "The Time Merchant."