WWD, from what I know, it's impossible for you to have seen a repeat. You may have seen it live, but there was no repeat of the whole serial. There was a plan to do the play again (like they did with Kneale and Cartier's version of Nineteen Eighty-Four
), but they didn't.
From Wikipedia (italics added by me):
The BBC intended that each episode be telerecorded onto 35mm film, a relatively new process that allowed for the preservation of live television broadcasts. Sale of the serial had been provisionally agreed with the Canadian Broadcasting Corporation, and Cartier wanted the material available to use in trailers and recaps. Only poor-quality copies of the first two episodes were recorded before the idea was abandoned, although the first of these was later shown in Canada. During the telerecording of the second episode, an insect landed on the screen being filmed, and can be seen on the image for several minutes. It is highly unlikely that material from the third to sixth episodes of the serial will ever be recovered to the BBC's archives. The two existing episodes are the oldest surviving examples of a multi-episodic British drama production, and some of the earliest existing examples of British television drama at all, with only a few earlier one-off plays surviving.
In November 1953, it was suggested that the existing two episodes could be combined and followed with a condensed live production of the latter part of the story for a special Christmas omnibus repeat of the serial. This idea was abandoned. Although Cartier and star Reginald Tate were keen to make an all-film omnibus version for television, this also did not come to fruition.
Of course, if you have actually seen the original serial, that would have been something...
Four minutes? That's ages! What if I get bored? I need a television, a couple of books. Anyone for chess? Bring me knitting.
-The Eighth Doctor, defiant in the face of death, in Doctor Who: The Night of the Doctor