my $reload_config = 0;
$SIG{USR1} = sub { $reload_config = 1 };
...
while( $yadda_yadda_yadda ) {
  check_something( $something );
  poll_for_widgets( $mywidgets );

  if( $reload_config ) {
    reload_my_config( $config );
    $reload_config = 0;
  }
}