Hi Emily,
We do not have such a feature that duplicates custom fields to other profile types.

EDIT: The closest way you can use to achieve this is by saving a profile type as a copy(Save as Copy) while editing the profile type(http://take.ms/54Hsq). This way, the custom field can be transferred over too. Then you just have to change the rest of the info.

Also, we will appreciate greatly if you continue your subscription with us as we would be able to provide continued support.