$new_cookie = cookie_creator_sub() if (some condition);

....

if ($new_cookie) { 
	print $q->header(-cookie=>$new_cookie);
} else {
	print $q->header();
}

my %cookie = $q->cookie('info');

....

sub cookie_creator_sub {

    .....

    my %cookie_info = (
	'tempfile'  =>	$tempfile,
	'timestamp' =>	$timestamp,
    );
		
   $newcookie = $q->cookie(-name=>'info',
			   -value=>\%cookie_info,
			  );	

   return $newcookie;
}