There is a link at the bottom on this page http://www.piano.christophersmit.com/repetitionMech.html which has an animation of how the repetition mechanism works in a grand piano action. I would expect a piano tech did a careful job of regulating those pianos before that performance!
The grand piano repetition action works well, and is consistent between the different notes on the keyboard, because it is basically "powered" by gravity acting on the weight of the moving parts. That isn't possible with an upright action, where almost everything in the action, except the keys, is rotated through 90 degrees.
The best you can do on an upright is to experiment to find out exactly where the repetition action "kicks in" when depressing the keys part way down, and then work on playing with enough force to operate the repetition action without pressing the keys right down to the key bed (except for the last note of the triplet, of course). There will probably be a tradeoff between "fast" and "loud" repetition (i.e. louder means slower repetition).
In an old upright piano, thoroughly cleaning the action and/or replacing some of the felt and leather parts, and carefully readjusting the repetition action, may help, but that is a long job and there is no way to know exactly how much improvement you would get before actually doing it. A botched attempt at regulating the repetition may make things worse, not better, if you aim for something that is too "good" to be realistically achievable.