I am using google chart with PHP. chart is working fine when the page is

load for the first time.

But I want to refresh the chart (not the entire page, only the chart), after

"n" seconds, automatically (based on java script intervals), dynamiccal I need

to push the server data,

Please assist me to fix this issue
where should I put java script interval part to refresh the chart

This is my code
---------------

<head>
<!--Load the AJAX API-->
<script type="text/javascript" src="jsapi.js"></script>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">

// Load the Visualization API and the piechart package.
google.load('visualization', '1', {'packages':['corechart']});

// Set a callback to run when the Google Visualization API is loaded.
google.setOnLoadCallback(drawChart);

**// This part needed to be changed to refresh the chart**



function drawChart() {
var jsonData = $.ajax({
url: "dataFetch/packageRenewals_WSC_AvaBill_Data.php",
dataType:"json",
async: false
}).responseText;

// Create our data table out of JSON data loaded from server.
var data = new google.visualization.DataTable(jsonData);

// Instantiate and draw our chart, passing in some options.
// var chart = new google.visualization.PieChart

(document.getElementById('chart_div'));
var chart = new google.visualization.BarChart(document.getElementById

('chart_div'));

chart.draw(data, {width: 450, height: 240});
}

</script>
</head>

<body>
<!--Div that will hold the pie chart-->
<div id="chart_div"></div>
</body>


Best Regards
Gayan