At this time, we do not provide the functionality to trigger a manual re-crawl. However, any changes to your site, for example if a new version of your CSS file is uploaded, will automatically trigger a re-crawl with the updated version.
Note that if your website is updated but the filename is kept the same (for example, a new version of your CSS file) then Heap will continue to use the cached (older) version of the file. As a best practice, we recommend renaming your file per the new version when uploading any code changes to your website.
If you need help, please post in Heap Community or visit our Get support page.