force a page reload

I have an button click event which adds data to a drop down box but after the data has been updated the drop down box isn't updated until the data is re bound to it if tried setting the drop down box to just reload but its on an (!IsPostback) because there is also a select button which needs the value of the selected item which doesn't work when I don't have the (!IsPostback) method so think I need to force the page to reload instead how do I do this or is there a better way cheers
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