Fetchdata dynamically for databound combo box

[smartgwtuser]

Hi,
I created a databound combo box and attached to listgrid filed. How can I dunamically refresh the combo box data? My code for creating combo box is below

public class TestSuggestionBox extends ComboBoxItem {

public TestSuggestionBox () {
setType("comboBox");
final DataSource testDS = TestGwtRpcDataSource.getInstance();
setAutoFetchData(true);
final Criteria criteria = null;
ataPartDS.fetchData(criteria);
setOptionDataSource(testDS );
setValueField("partDesc");
setDisplayField("partDesc");
setShowPickerIcon(false);
setTextMatchStyle(TextMatchStyle.SUBSTRING);
setTextBoxStyle("gwt-SuggestBox");
setTitle("Part Description suggestion");
setPickListHeight(200);


}

}

TestSuggestionBox testSuggestionBox = new TestSuggestionBox ();

Criteria criteria = new Criteria();

testSuggestionBox .getOptionDataSource().fetchData(criteria);



final ListGridField partDesc = new ListGridField("partDesc");
partDesc.setEditorType(testSuggestionBox );
partDesc.setCanEdit(true);


How can I refresh combobox dynamically? I tried so many options, but unable to find the solution.

Thanks in advance for any help.