$ua->click;

           die "I'm failing ", $ua->reload
               unless $ua->success;

 
sleep 15;
[download]

What are you up to with that? It looks to me like the script will die (or "crash" as you put it) the first time that $ua->success fails to return true. Is that what you want? From your description it sounds like what you want is something more like

while ($ua->response->content =~ m/nextbut/i) {
  until ( $ua->click->is_success ) {
    warn "Submission failed: I'll sleep for a while";
    sleep 15;
    $ua->reload;
  }
  # etc., etc.
}
[download]