if your just looking to clear/remove the stat's file every month ..

Code
on *:LOAD: {
if (!%currentmonth) { set %currentmonth $gettok($fulldate,2,32) }
}

on *:START: {
.timer -o 0 3600 checkdate
}

alias checkdate {
 if (%currentmonth != $gettok($fulldate,2,32)) {
  set %currentmonth $gettok($fulldate,2,32)
  .remove chanstats.txt
 } 
}