Changing the content of a xml from as3 and saving it

Hi guys...

I have a simple question... I access a xml from my code and read a value... and I need to change it to another one, since I will access the xml from the other stage... can it be done?

I have used replace but when I check the original xml, the value remains the same:

var xmlldr:URLLoader = new URLLoader();
xmlldr.addEventListener(Event.COMPLETE, loadComplete);
xmlldr.addEventListener(IOErrorEvent.IO_ERROR, loadError);


var xmlContent:XML;
var bT:int;


xmlldr.load(new URLRequest("c.xml"));


function loadComplete(e:Event):void {
xmlContent = new XML(xmlldr.data);
xmlldr.removeEventListener(Event.COMPLETE, loadComplete);
xmlldr.removeEventListener(IOErrorEvent.IO_ERROR, loadError);
trace(xmlContent.gCg.fBT);
ChangeBT();
}

function loadError(e:IOErrorEvent):void {
  }


function ChangeBT():void {
  bT = 2000;
  xmlContent.gCg.fBT.replace("1000", bT);
  trace(xmlContent.gCg.fBT);
}

Can it be done? meaning? can I, by changing the value on the first stage, have the original xml file value changed as well?

Thanks!!!