By default, a UDH profile reads the list of iQ attributes from the iQ profile that has the same name as the UDH profile.
To make a UDH profile see a new attribute, that attribute needs to be added to the iQ profile with the same name in the version of that iQ profile that was last saved to production. You don't need to publish to production, but you do need to save the attribute there. I usually add the attributes to the Dev and QA "branches" as well so that the attribute doesn't get lost if those attributes are "promoted".
Usually, however, I don't bother using iQ attributes if they are not already there. I just add a new event attribute with the same name as the iQ attribute, in the UDH itself. The only time where this currently doesn't work is if the iQ attribute needs to be treated as a date. In that case, UDH cannot parse a UDH attribute as a date and it does need to be an iQ attribute, so I set those up as described above.
Finally, if the above doesn't help, and if this is something that you need kept in sync between two iQ profiles on an ongoing basis, then you can email Tealium support and they can set up an automatic syncronisation between the two iQ profiles.