K2 surprise me (good surprise) with the "Save and new" buttom in backend... but it suffers a lot with the frontend form.
Why do not simplify the operation? In most cases, the sites will offer frontend editing and the users WILL enter a lot of data.
The tabs are problem. They contribute to the author to forget something.
Also, integrated in the site. Normally the user enters an item and want to see it. It has been necessáry to save, to exit the form windows and navigate to the item. I suggest buttons with "save and see", "save and new". An item under "save and see" action can have a button "back to edit form".