1:45 seems incredibly risky for a domestic to international connection in PVG on two separate tickets. Domestic Chinese flights are notorious delay prone (slightly better than in the past, but still unreliable). Even if you don't have checked bags, you'll still have to check in at PVG for your Tokyo flight at the counter, and there'll be a strict cutoff for that.

I would take the earlier flight, and spend your time in the lounge.

Alternatively, if you can find a SHA-HND redemption, you can take high speed rail (about 3 hours) from Wenzhou to SHA's train station.