For the date the email is sent plus 30 days you can use our information in Formatting Merge Fields for the nDate merge field:
[nDate Long+30]
It is not strictly "next month on the same date". For instance, today is Feb. 7th, and using that merge field results in an email with "March 9, 2017" as the date because February only has 28 days this year. There is not a way to state just the month using this merge field, so we'll keep your Feature Request open.
