Exactly what kinds of deterioration is the current patio cover experiencing? I recall some of the older (I think, acrylic) panels crazing over time, and then becoming brittle to the point of fracture.
You probably need to start from scratch if you're enlarging the new covering extensively, or if any of the framing members and columns are deteriorated to the point of dying. A properly-designed patio cover can last many years, while a poorly-designed or constructed one will be begging for repairs within a year or two of completion. The last house we owned (in WA state) had an aluminum-framed cover with polycarbonate panels, and it showed no signs of distress after almost 20 years of service (if the previous owner was truthful on its age).
In your climate, you want something that will resist at least 40 lb. per S.F. of snow load, along with some beefy hail resistance and ability to perform under many consecutive days of both sub-freezing weather and those scorchers above 100* F. I lived in Wisconsin for the first 22 years of my life, and I haven't forgotten the weather extremes. Why not give Menard's a try, to see if they offer a computerized patio cover design service? And they might have a list of approved contractors for doing the work should you and hubby not want to mess with it yourselves.