Anatoly Mironov has a great post on how to export web parts when the export functionality is disabled (like XsltListViewWebParts). Find the full post here.
Use the following url, changing the guid string with the web part id:
where the web part id can be retrieved by looking at the source code, finding your web part, and looking for the:
<div webpartid="0c3adfe9-8f5d-4432-918a-42410e4e324d" ........ >