I had a similar experience with one of my themes, it was insta rejected with the same message “Previously Hard Rejected item”
After i did a good amount of changes i uploaded the item with a new “thumb image 80x80” and new “590x300 banner” so the reviewer will know there are important differences between the last versions.
Personally i keep the old versions live until approved, for example: http://estudiopatagon.com/themes/wordpress/reinv3/ then my final version is http://estudiopatagon.com/themes/wordpress/reinv5 and comment to the reviewer there are major improvements comparing the old theme.
With respect, speaking in terms of design, your theme is a 6 or 7 of 10, there is still space for improvement: https://prnt.sc/r0xqbx (the menu looks quite old with that dots), typos can be improved as well: https://prnt.sc/r0xs4l the forms too: https://prnt.sc/r0xsn3 Avoid using text-decoration underline for links and use italic only when needed: https://prnt.sc/r0xtgk I’m using a Full HD monitor, but i think some regular texts are too large in terms of hierarchy.
Hope my experience and comments will help you!