[Clear data from chart?]

 OK,this is a clear,but I need a refresh data so i have this function and she works:

" function onLoadDoc() {
     var vl1;
    var vl2;
    var vl3;
    var val1;
    var val2;
    var val3;
    var chart1;
    chart1 = new cfx.Chart();
    chart1.setGallery(cfx.Gallery.Lines);
    chart1.getLegendBox().setDock(cfx.DockArea.Bottom);
      val1 = document.getElementById('v1').value;      <-v1,v2,v3 are text input (number)
     val2 = document.getElementById('v2').value;
     val3 = document.getElementById('v3').value;
     vl1 = parseInt(val1);
     vl2 = parseInt(val2);
     vl3 = parseInt(val3);
   
     var data=[{
        "Label": "+18",
        "text": vl1
      
    }, {
        "Label": "0",
        "text": vl2
  
    }, {
        "Label": "-15",
        "text": vl3
 
    }];
     chart1.setDataSource(data);
        var chartDiv = document.getElementById('ChartDiv1');
     chart1.create(chartDiv);  
     }
    //*****END OF FUNCTION***** """"

This function works but I need next:User change V1,V2 AND V3 (number value) and press a button,then i need just to refresh data in same chart

[Clear data from chart?]

I'm a n00b so I have a two question:

1. How could I clear my data from chart? (or refresh?)

2. When I set data on my chart I have a data,which I'm not enter.

I use your sample code from this site.

Thanks