Code:
on *:text:!XP [color:red]* *[/color]:#: {
  var %alreadyxp [color:red]=[/color] $readini(Stats.ini, XP, $2)
  [color:red]var %XP =[/color] %alreadyxp + $3
  writeini Stats.ini XP $2 %XP
}


This should work.