This requirement can be accomplished with qListForm. Initially I thought about using Custom Actions which provides the most flexible and powerful means to add behaviors. However it is much involved with custom coding and may not generate the desired result. So my suggestion is to follow a simple workaround.
As I posted earlier regarding your first question, you would need to have the same settings like that with two pages containing the qListForm. However instead of directing the first page directly to the second page, you would introduce a 3rd page as the middle man. On this page, you would display the message "Would you like to add additional items to this request?" with button "Yes" and "No". Based on the answer, it redirects the page either to the first page to allow user add additional item or to the second page to continue filling out other details of the same item.