can't change artist id to override cache after no future shows

I had an artist in there, and it was showing events fine. Then the artist ran out of shows in the future so this got cached:
a:1:{s:113:”http://api.songkick.com/api/3.0/artists/583819/calendar.json?apikey=x9RfYolxO0uyKjEt&order=asc&per_page=50&page=1″;a:3:{s:6:”events”;a:0:{}s:5:”total”;i:0;s:9:”timestamp”;i:1355784725;}}

But now if i change the artist id to someone else, it doesn’t update the cache, even after waiting a few days, and refreshing a lot, it never updates that record in the database, still locked into the artist with no future shows.

Even if i delete that record from the database, and reinstall the plugin, it still puts the old artist id back…

http://wordpress.org/extend/plugins/songkick-concerts-and-festivals/