Untested, but try something like this.

my $timeout = 20;   # seconds
my $conn = $irc->newcon
(
  # ...
);

sub check_alivedness
{
  unless ( $conn->connected )
  {
    # do something
    # $con->connect
  }
  $con->schedule( $timeout, \&check_alivedness );
}

$con->schedule( $timeout, \&check_alivedness );

$irc->start;
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