Getting perch to reindex itself

I have created some buckets which I no l longer need. I have deleted the folders from the directory and removed any reference to them in the perch templates / buckets.php file

However, perch's asset library has stopped displaying thumbnail images and I can't delete buckets that no longer exist. They remain as selectable in the assets library.

Will reindexing fix this? If so, how do I go about it?

Thx