Hi Stacey,
I am not sure if you already have your answer. If not here I go.
For the local you can claim management on the account which would need to be re-verified. This would let you get in there at least an potentially clean up anything that needs it. You would not loose your reviews. Based on your description of old SEO errors I can imagine it may be link based errors which could have developed a algorithmic penalty which in that case a new domain, in the in term only, may be useful. If you are sure it is not algorithmic though I would think that perhaps re-evaluating the on-page and content would be the next step.
Hope this helps if you haven't gotten help already