I have searched to no avail the answer to this relatively simple question.
I have a sit scheduled that is “Live”. The sitter is confirmed, all is good with that sit. But now I want to schedule a new sit for the following month… How do I create a new listing?
Thanks in advance
You cannot and don’t need to create a new ‘listing’ - you simply add new dates, and your listing will become active again for these new dates. Here’s how: 
You can also add multiple dates at once rather than listing only 1 date at a time. This is a good idea, as you can book different (or the same) sitters well in advance for different sit dates. If you have multiple dates listed, sitters are required to click the date(s) that they are applying for when applying to your sit, so you don’t get confused.
If there are changes for your listing then you can indicate this within the listing eg
Date z 2 dogs 3 cats
Date x no dogs 3 cats
Date y 2 dogs no cats
Date m no pets