use strict;
use warnings;
use XML::Twig;

my $xmlStr = <<XML;
<project>
 <run_count>
  <count>13</count>
 </run_count>
</project>
XML

my $twig= new XML::Twig(
    PrettyPrint   => 'indented',
    twig_handlers => { count => \&count }
);
$twig->parse($xmlStr);
$twig->print();
exit;

sub count {
    my ($twig, $cnt) = @_;
    $cnt->set_text(14);
}  


__END__

<project>
  <run_count>
    <count>14</count>
  </run_count>
</project>
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Side note: Welcome to the Monastery. In general, it is better to use 'code' tags instead of 'pre' tags when posting code. (see Perl Monks Approved HTML tags)

Thanks a lot toolic

The code works great

use XML::LibXML;
my $template = 'sample.xml';
my $parser = XML::LibXML->new();
my $doc = $parser->parse_file($template);

my($object) = $doc->findnodes("/project/run_count/count/text()");
my $text = XML::LibXML::Text->new('14');
$object->replaceNode($text);

open (my $Output, ">$template") or die "Could not write $template";
print $Output $doc->toString;
close ($Output) or die "Could not close generated $template ";
[download]