If I receive a LN payment from an anon sender... is there a way to send back to this individual? I see the preimage, hash, and payment request but all of those are transaction specific and unrepeatable. Any idea how it would be possible to send back the other way without knowing the individual?
No, there is no definitive way to detect the source of a payment on the Lightning Network.
However, there exists techniques (either active or passive, such as probing or some heuristics) which may be used to try to deanonymize parties involved in a payment.
So, while you can't reliably identify a party, you cannot assume it's totally anonymous either.