Open BAStats.php from the plugin directory for editing.
Look for a line near the top that says:
var $table_version = 6;
The number 6 may be a different number. Whatever it is, increase it by 1.
Save the file and reactivate the plugin to recreate the tables.
Apart from that, BAStats development is on a break. Why?
One reason- Because Asymptomatic gets 3000+ sessions (not hits, sessions) per day, and BAStats makes the MySQL process on the server eat processor time. I worry that as your traffic builds up, BAStats will start to have this effect on your system, too. Please report this if you're using the beta and it happens to you.
Another reason- I'm embroiled in other development (plugins, work, secret WP projects) at the moment, and figuring this one out isn't currently a priority for me.
Another reason- I wrote all of the reports myself, and some are slightly broken in ways that are difficult to fix. I get a lot of suggestions for what to add to the plugin, but never any suggestions on how to fix what's currently wrong with the plugin. Introducing new features when the existing features aren't perfect seems irresponsible. But maybe if people forwarded some fixes for the reports...
Keep in mind that BAStats has never left beta, although it's been there for a while and has had several updates. Everyone who uses it seems to like it, and I might be the only person who has problems (I'm on a Windows server, see, which may soon change), so I'm sure to get back to it eventually, just not this afternoon. I hope you understand.
Note that the current version of BAStats outputs a SQL statement to the bottom of the stats page on purpose. Please stop reporting that the plugin is generating errors - this is not an error.
And finally, my email is encoded at the very bottom of my blog. No need to bump posts here (which someone else will usually be answering, since I rarely stop by here these days) - when you don't get a response to your question, just email me.