Buzznut3000

Here is the background before the questions.  I moved to Germany in 2016 with my wife from the US and received a residence permit.  The language requirement was waived because I had a university degree. When I renewed my US passport in 2018 I had to get a new permit valid till April 2021.  In 2019 my wife and I split and I moved back to the US.  We're not yet divorced but soon will be (I filed in Texas).  Lately I've been thinking that I would like to live back in Germany for either part of the year or a year off and on.  My question is, what would be involved in renewing the permit?  Would I have to simply re-register my new residence in Germany and then apply for a renewal?  Would they not like that I've lived now 9 months outside the country?  What about language requirements?  I was probably A2 when I left, seems to me they said I needed B1 for a permanent card, but would I be able to apply for another temporary?  If anyone has any thoughts or similar experiences it would be greatly appreciated.