<?php
$tag = '<string name="abs__action_bar_home_description">My old title</string>';
$new_title = 'My new title';
$pattern = "/(<string[\s\w=\"]*>)([\w\s]*)(<\/string>)/i";
$replacement = "$1".$new_title."$3";
echo $result;
?>
PD9waHAKCiR0YWcgPSAnPHN0cmluZyBuYW1lPSJhYnNfX2FjdGlvbl9iYXJfaG9tZV9kZXNjcmlwdGlvbiI+TXkgb2xkIHRpdGxlPC9zdHJpbmc+JzsKJG5ld190aXRsZSA9ICdNeSBuZXcgdGl0bGUnOwoKJHBhdHRlcm4gPSAiLyg8c3RyaW5nW1xzXHc9XCJdKj4pKFtcd1xzXSopKDxcL3N0cmluZz4pL2kiOwokcmVwbGFjZW1lbnQgPSAiJDEiLiRuZXdfdGl0bGUuIiQzIjsKJHJlc3VsdCA9IHByZWdfcmVwbGFjZSgkcGF0dGVybiwgJHJlcGxhY2VtZW50ICwkdGFnKTsKCmVjaG8gJHJlc3VsdDsKCj8+