[SalesForce] Action support rerender

Following is what i´ m trying to accomplish:

and on change picklist:

Switching between picklist values should update the Person in the chart:
I got this working with following code:

VF Component:

<apex:component Controller="ForecastHierarchyController">
    <apex:includeScript value="https://www.google.com/jsapi"/>
    <script>
        google.load('visualization', '1', {packages:['orgchart']}); 
        google.setOnLoadCallback(drawChart);

        function drawChart() {
            var data = new google.visualization.DataTable();
            data.addColumn('string', 'Name');
            data.addColumn('string', 'Parents');
            data.addColumn('string', 'Type');
            data.addRows([
                // All data rows are calculated in Apex controller
                // and returned as a string with line endings CR+LF
                {!accRows}
            ]);

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



            chart.draw(data, {allowHtml:true,
                              size:'medium',
                              allowCollapse:true});

        }
    </script>


     <apex:form >
        <apex:selectList value="{!FilterType}" multiselect="false" size="1">
              <apex:selectOption itemLabel="PersonOne" itemvalue="PersonOne"/>
               <apex:selectOption itemLabel="PersonTwo" itemvalue="PersonTwo"/>
               <apex:actionSupport event="onchange" action="{!CreateChartData}" onsubmit="drawChart();" />
        </apex:selectList>
     </apex:form>  
     <apex:outputPanel id="chart">
        <div id='chart_div'>
        </div>
     </apex:outputPanel>
</apex:component> 

Apex Controller:

public class ForecastHierarchyController { 
    private account acc;
    public String FilterType {get;set;}
    public String accRows {get;set;}

    public ForecastHierarchyController() {
        FilterType='PersonOne';
        CreateChartData();
    } 

    public void CreateChartData(){      
        system.debug('####FilterType'+FilterType);      
        accRows= '';
        if (FilterType=='PersonOne'){
            accRows+=            '[{v:\''    + 'PersonOne'+ 
                                 '\', f:\''  + 'PersonOne' + 
                                 '\'},\''    + '' +
                                 '\',\''     + '' + 
                                 '\'],\r\n';    
        }
        else{
            accRows+=            '[{v:\''    + 'PersonTwo'+ 
                                 '\', f:\''  + 'PersonTwo' + 
                                 '\'},\''    + '' +
                                 '\',\''     + '' + 
                                 '\'],\r\n';                
        }           

        accRows+= '[\'\',\'\',\'\']';
        system.debug('accRows'+accRows);
    }


}

There is only one problem: on change picklist value all the page is refreshed (picklist+ chart).
Instead,on change person, i would like to refresh only the chart and not the whole page.

I´ ve tried adding rerender attribute to actionSupport tag:

 <apex:actionSupport event="onchange" action="{!CreateChartData}" onsubmit="drawChart();" rerender="chart" />

but it doesn´t work,on change picklist value chart isn´t showed anymore.

Do you know how can i refresh only the chart and not the whole page?

Thanks in advance for any advice.