How can I get the sum of label with jquery in grid view when text box changed

function Calctotal_pre(PreviousValue, txtvalue, TotalValue)
{
var uservalue = parseFloat(document.getElementById(txtvalue).value);
var TotalVar = document.getElementById(TotalValue);

var TotalValue = parseFloat(PreviousValue + uservalue );
TotalVar.innerHTML = TotalValue;

var total_allPY = 0;
$($("[id*=GvList] [id*=lbl_sum]")).each(function ()
{
if (!isNaN(parseFloat($(this).val())))
{
total_allPY += parseFloat($(this).val());
}
});

$("[id*=GvList] [id*=lbl_PY_total]").html(total_allPY);
}


----------------CODE PART--------------

protected void GvList_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
Label lblList = (Label)e.Row.FindControl("lbl_pre");
PreVal += Convert.ToDecimal(lblList.Text);

txt_pre.Attributes.Add("onkeyup", "Calctotal_pre(" + PreVal + ", '" + txtqut.ClientID + "','" + lbl_sum.ClientID + "')");
}
}