we realized we accidentally put a wrong item on an invoice earlier in the year. is it possible to rerun revenue in this case?

Just Issue a Credit for the wrong item and then re-invoice using the proper item. You'll then have 3 revenue arrangements (2 invoices and 1 credit) but it will net out properly on your GL in the end.

if it’s a credit memo then invoice it to net it and re-issue a credit memo? would it possibly be cleaner to just change the items on the original credit memo?

That would not be cleaner and could possibly create a huge mess. Ideally, if your past accounting periods are closed, you can't do it anyway, so best practice, both from a NetSuite and accounting perspective, is to credit the old invoice and issue a new one. What is the difference between the two items? price? revenue handling?

yes the difference is the fair value price so revenue allocation is messed up