You only need one text event, and here is my take on your script:

on $*:text:/^!((cl)?prize|winner)/iS:#: {
  if (!%f) { set -u3 %f $true | goto $iif($replace($regml(1),winner,w,prize,p,clprize,clp),$ifmatch)
    :w | var %x = 1 | while ($nick(#,$r(%x,$nick(#,0)))) { if ($ifmatch = $me) { goto r }
      else { set -e %a $ifmatch | tokenize 32 %a | .msg # Congratulations, the winner is $str($*,1) , $&
      and you win the prize: $iif($($+(%,prize.,$network,.,#),2),$ifmatch,nothing) } | inc %x | halt } 
    :p | if ($nick isop #) { set $+(%,prize.,$network,.,#) $$2- | .msg # New prize set for $+(",$2,") | halt }
    :clp | if ($nick isop #) { unset $+(%,prize.,$network,.,#) | .msg # Prize Cleared! | halt }
    :r | .msg # Congratulations, the winner is %a , and you win the prize: $iif($($+(%,prize.,$network,.,#),2),$ifmatch,nothing) | halt
  }
}

A trigger flood control is needed in case people tamper with this script to flood out the client running the code. (can only be triggered every 3 seconds)