There was a proposed sequel called The Dam.
A number of years ago I read that there was going to be a Cliffhanger sequel called The Dam. I don't know what the storyline was going to be but I saw an interview with Stallone around 1999 or 2000 where he claimed he turned it down because he didn't care to do a film in that type of environment again. He often cites Rambo III and Cliffhanger as the most dangerous action films he's ever made.
And I remember leading up to Cliffhanger, Stallone kept going on about how he was afraid of heights. If an actor was truly bothered by heights I'm not so sure how they could star in a movie like Cliffhanger and do most of their own stunts. Although certain scenes were shot in a studio such as when Gabe and Jesse are using that old rope which is close to breaking.