First, that's really awesome that you have 26 weeks already.
Second, I strongly recommend against doing this. Before engagement programs, you essentially had to recycle leads through the same content. Engagements discourage this because they won't send the same content twice. You could clone the Program and push everyone over to the new one. But why? Come up with fresh content.
Another option is to add a new stream that uses the existing content in a new order.