good work :)

but here's a couple of tips:
You don't need all of the /'s
Using local variables wud be better as they are auto unset when not needed (/var rather than /set)

Also if you want you can replace:

  %num1 = $rand(1,49)
  :tryagainA
  %num2 = $rand(1,49)
  if %num2 = %num1 { /goto tryagainA }
  :tryagainB
  %num3 = $rand(1,49)
  if %num3 = %num2 || %num3 = %num1 { /goto tryagainB }
  :tryagainC
  %num4 = $rand(1,49)
  if %num4 = %num3 || %num4 = %num2 || %num4 = %num1 { /goto tryagainC }
  :tryagainD
  %num5 = $rand(1,49)
  if %num5 = %num4 || %num5 = %num3 || %num5 = %num2 || %num5 = %num1 { /goto tryagainD }
  :tryagainE
  %num6 = $rand(1,49)
  if %num6 = %num5 || %num6 = %num4 || %num6 = %num3 || %num6 = %num2 || %num6 = %num1 { /goto tryagainE }
  :tryagainF
  %num7 = $rand(1,49)
  if %num7 = %num6 || %num7 = %num5 || %num7 = %num4 || %num7 = %num3 || %num7 = %num2 || %num7 = %num1 { /goto tryagainF }
  %chan = $readini($mircdir\lotto.ini, lotto, chan)
  msg %chan Your lucky numbers are:4 %num1 %num2 %num3 %num4 %num5 %num6 ( $+ %num7 $+ )

with

  var %i = 2, %num1 = $r(1,49), %lnumbers = %num1
  while (%i <= 7) {
    var %num [ $+ [ %i ] ] $r(1,49)
    while ($istok(%lnumbers,%num [ $+ [ %i ] ],44)) {
      %num [ $+ [ %i ] ] = $r(1,49)
    }
    %lnumbers = $addtok(%lnumbers,%num [ $+ [ %i ] ],32)
    inc %i
  }
  %chan = $readini($mircdir\lotto.ini, lotto, chan)
  msg $chan Your lucky numbers are:4 %num1 %num2 %num3 %num4 %num5 %num6 $+($chr(40),%num7,$chr(41))

msg $chan $sorttok($deltok(%lnumbers,7,32),32,n) $+($chr(40),%num7,$chr(41))
^ this says the first 6 numbers in order of my code and then the 7th number

and you can replace

  %num1 = $readini($mircdir\lotto.ini, lotto, lucky)
  :tryagainA
  %num2 = $rand(1,49)
  if %num2 = %num1 { /goto tryagainA }
  :tryagainB
  %num3 = $rand(1,49)
  if %num3 = %num2 || %num3 = %num1 { /goto tryagainB }
  :tryagainC
  %num4 = $rand(1,49)
  if %num4 = %num3 || %num4 = %num2 || %num4 = %num1 { /goto tryagainC }
  :tryagainD
  %num5 = $rand(1,49)
  if %num5 = %num4 || %num5 = %num3 || %num5 = %num2 || %num5 = %num1 { /goto tryagainD }
  :tryagainE
  %num6 = $rand(1,49)
  if %num6 = %num5 || %num6 = %num4 || %num6 = %num3 || %num6 = %num2 || %num6 = %num1 { /goto tryagainE }
  :tryagainF
  %num7 = $rand(1,49)
  if %num7 = %num6 || %num7 = %num5 || %num7 = %num4 || %num7 = %num3 || %num7 = %num2 || %num7 = %num1 { /goto tryagainF }
  %chan = $readini($mircdir\lotto.ini, lotto, chan)
  msg %chan Your lucky numbers are:4 %num1 %num2 %num3 %num4 %num5 %num6 ( $+ %num7 $+ )

with

  var %i = 2, %num1 = $readini($mircdir\lotto.ini, lotto, lucky), %lnumbers = %num1
  while (%i <= 7) {
    var %num [ $+ [ %i ] ] $r(1,49)
    while ($istok(%lnumbers,%num [ $+ [ %i ] ],44)) {
      %num [ $+ [ %i ] ] = $r(1,49)
    }
    %lnumbers = $addtok(%lnumbers,%num [ $+ [ %i ] ],32)
    inc %i
  }
  msg $chan Your lucky numbers are:4 %num1 %num2 %num3 %num4 %num5 %num6 $+($chr(40),%num7,$chr(41))
$sorttok($deltok(%lnumbers,7,32),32,n) $+($chr(40),%num7,$chr(41))

They are shorter, it also uses local variables instead of global, although i think its about the same efficiency.

anyway another note is u dont need to write %chan to an ini file you can just set it

  writeini $mircdir\lotto.ini lotto chan $chan 

can be:

  set %chan $chan 

and hen you can remove any of these since its already set:

  %chan = $readini($mircdir\lotto.ini, lotto, chan)