I’d read that it’s possible to move from one G+ account to another; however, it seems that it’s far more difficult than it appears (mostly because Google have removed the tool they used to offer.
At present, all I can do is to use the vcf cards from the Google Takeout (which are handily grouped into circles. However, as far as I can tell, adding them to my contacts list on Google doesn’t add them to a circle, merely adds the to the list of people from which I can choose to follow. That said, Google are updating the contacts list (and mine’s in a pretty good muddle!) so perhaps time to have a sort out.