Go to Tools tab, Options panel, expand it down, click on iLogic Configuration button.

Within the Advanced iLogic Configuration dialog that shows, use the '+' button to add the directories where it should look for your external iLogic rule files. It will not be able to find rules that are in sub folders of a directory that you list there, so if you have rules in sub directories, then list those sub directories directly in here also.

Then, make sure you set the same file extension that you were using before for your external iLogic rule files.
Edit: Or...if you have exported those settings before directly from this dialog, then you can use the Import button at the bottom of this dialog to import your previous settings again.
If you have not ever exported your settings directly from this dialog, then in the last couple version of Inventor, those settings are also included with your 'Application Options' exported file. So, if you have exported your Application Options from that dialog before, you can go to your Application Options dialog again, and use its Import button to import your previous settings file. That should restore both your application options stuff, but also your iLogic configuration stuff (if you are using one of the latest versions of Inventor).
Wesley Crihfield

(Not an Autodesk Employee)