Hello, Chris,
I hope I answered you in Sharepoint.stackExchange.com:
The data fields bound to repeating controls are used for storing/saving data of repeating items structures and cannot be used for lookup-ing what you are looking for.
So, you are trying that it pulls itself by its own hair.
To have independent on repeating items content of a drop down list box (DDL) in repeating section you should bound DDL to a data source stored outside of data fields used for storing repeating section items.
I would have used a data source outside of template in order to have ability to change the list of choices without republishing a template.
Here is a screenshot of DDL in repeating section with independent list of choices bound to a sharepoint list field

Fig.1. Independent, i.e. external data source used for list of choices of Drop Down List Box in a repeating section