I'm not sure if that is possible. Unfortunately I can't test this out as I don't have Logic 7 installed on any of my systems anymore.
However, you could try re-indexing the Logic 7 Loop Library... but I'd exercise caution doing this as it might interefere with Logic 8's Loop Browser...
Here's how you can try it out:
1. Clone your system drive! Backing up is always a good idea. You might like to try using Time Machine of the free Carbon Copy Cloner.
2. Open Logic 7 and drag the Apple Loops folder (as mentioned above) onto the Loop Browser. This should start the re-indexing...
Personally, I'd recommend using Logic 8. After you get used to the new interface you should find it much more intuitive to use.
Also, you can load Logic 7 projects in Logic 8... but remember if you make any changes to save them as separate proejcts (save as...) - basically this will keep the original project in Logic 7 format and enable you to open it in L7.
Sorry I can't be of more help.