"The Fugitive" did had a sequel episode titled "The Breaking of the habit" filmed during the last season in color who was a sequel to the episode "Angels Travel on Lonely Roads".  I guess it was a rare case for the era to see an episode sequel.

Then another case of interesting sequel, the episode of Diagnosis Murder "Hard-boiled murder" reprised a unfinished case from a Mannix episode titled "Little girl lost" where Mike Connors returned on his role of Mannix. No need to mention Knight Rider with sequel episodes featuring Garth Knight and KARR. ;)