As help with getTimer

Does anyone Know how to reset time in Flash?
Because i try to make a game where i used getTimer to get the time that a player took to play the game. At the end i display the resurt in a dynamic field, including the length of the game . I’ve also put a restart button wich allow the user to replay another game. The problem that i’m having is that i can reset the time used by the player. For example if in the first game your time is 1:33 and then you replay the tim does’n t start counting on 0:00 but on 1:33 and then continue.
here is the code

on frame 1;
// a global variable wich will keep the value of the time
_global.tempsFinal = 0;

// get the time while your playing since you started playing

var intervalTime = setInterval(getSecondes, 100);

function getSecondes() {
var my_date:Date = new Date();
var econdes:Number = Math.floor(getTimer()/1000)%60;
var minutes:Number = Math.floor((getTimer()/1000)/60);
}

// to display the time in a dynamic field

temps.text = minutes+":"+secondes;

// the code for the button to display the results
ShowResult_btn= function(){
gotoAndStop(10);
tempsFinal = minutes.toString()+":"+secondes.toString();
}

on frame 2

this is the code on the button if you want to restart

restartBtn.onPress = function() {
_global.tempsFinal = 0;
gotoAndStop(1);
}
Does any one knows a better way to do the same task?
thnks
wo1olf