I use echo DOCUMENT_NAME in my call to burstnet banners to force update of the banner call for each page. As usual your milage may vary.

<!-- BEGIN BURST CODE -->
<center>
<a href="http://www.burstnet.com/ads/adxxxxb-map.cgi/<!--#echo var="DOCUMENT_NAME"-->" target=_top>
<img src="http://www.burstnet.com/cgi-bin/ads/adxxxxb.cgi/<!--#echo var="DOCUMENT_NAME"-->" ismap width=468 height=60 border=0 alt="Click Here"></a>
</center>
<!-- END BURST CODE -->