Source: WowAce

This seems like a simple issue, but there isn't a way to do this currently. One could add an exception for this item, but I'd rather be able to set items as repeatable arbitrarily so future updates can build on it, e.g., by allowing all pets to be tracked repeatedly etc.

You're right, this does seem to work. Fixed in a9fbb1e.

Shouldn't it be enough to just set the item to repeatable = true?
As far as I can tell this setting will only make Rarity re-enable tracking on the item if it is found, so shouldn't really affect anything else.