How to refresh an IFrame using Javascript?
This should help:
document.getElementById('FrameID').contentWindow.location.reload(true);
EDIT: Fixed the object name as per @Joro's comment.
var iframe = document.getElementById('youriframe');
iframe.src = iframe.src;
provided the iframe is loaded from the same domain, you can do this, which makes a little more sense:
iframe.contentWindow.location.reload();
Works for IE, Mozzila, Chrome
document.getElementById('YOUR IFRAME').contentDocument.location.reload(true);