how do I resume download of in-app purchase?

hi

yesterday I upgraded to the latest GarageBand then I bought the in-app purchase for extra content (loops, drums etc). The download started and looked like it was going to take a couple of hours to download. Eventually my computer went to sleep (and so did I) and this morning when I got back in there was a message from GarageBand saying that I wasn't connected to the internet so it couldn't download the content.

I can't seem to find any way to first of all check if the content has completely downloaded, and if not, how do I re-start it?

thanks

nick