Code:
on 1:TEXT:%mp3sendtrig:#:{
  if %mp3sendyn == on {
    if %wanow != nothing {
      var %file = $nopath(%wafile)
      var %check = $readini(ini\songs.ini,%file,$nick)
      if (%check != true) {
        /writeini -n ini\songs.ini " $+ %file $+ " $nick true
        /dcc send $nick %wafile
        [color:red]/timer -o 1 60 /writeini -n ini\songs.ini " $+ %file $+ " $nick false[/color]
      }
    }
  }
}

This will change the setting in the ini to false after 60 seconds, letting the user get it again after this time.

Notes about your changes, setting two variables using ctime and ctime - 60 is useless, if you had compared them for any reason the result would always be exactly the time. !<= is incorrect, the opposite of 'less-than-or-equal-to' (<=) is 'larger-than' (>). Plus in that particular if statement, %check would be a string and %time2 would be an integer, such a comparison using math operators is not possible.

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