s/ means slide, not only slide up, it can be slide from 7th to 9th and then to 5th... The " s/ " (or sometimes just the bar " / " ) means slide, whether it's to a upper fret or not.
And the slides are done applying full pressure in all frets, you don't have to reduce the strenght when you go through the other frets. If you have to slide from 6th to 9th frets, you simply put your finger on 6th, pull the string and then go moderately quickly (it depends on the song, obviously) to the 9th, going through 6th, 7th, 8th and 9th. Otherwise it wouldn't be a proper slide, just pushing two different notes. A slide contains all frequencies from the note X to the note Y

So you're messing with Miracle Drug now, huh? It was the first U2 song (the riff and the solo, actually) that I ever learnt... Great memories

