Javascript example
HTML
<input type="submit" id="byBtn" value="Click Me!" onclick="doSomething()"/>JavaScript
function doSomething(){
var foo = "Este aqui Ă© o valor do cliente 000.000.00 01";
var number = foo.match(/\d\d\d\.\d\d\d\.\d\d \d\d/);
var to_replace = "129.000.000 02";
var lastnumber = foo.match(/\d{2}$/);
to_replace = to_replace.replace(/\d{2}$/, lastnumber);
alert("Valor original: " + number);
alert("Novo valor: " + to_replace);
}