Well use a timer.

//timer 0 600 changevar

Will call an alias called "changevar" every 600 seconds, and keep running forever till you stop it manually or close mirc.

alias changevar {
; your if conditions to chose when you want to set what variable
if (blah) { set %myvar *views* }
elseif (bleh) { set %myvar *whatever* }

This is really a bit strange though, like, how do you expect your script to know what var it should set at what time? It's really more of a manual thing that you should set.

I can't help you further unless you specify under what conditions you want what as matchtext. Btw in mIRC /help /timer

You mentioned a list...what kind of list, where is this list, how should the script choose what from the list, what are the criteria? Should it be random? May it be the same value 2 times in a row, etc etc etc.

Be as specific as can be please.