Besides of the flight, the most ideal transport is taking a bullet train from Shanghai to Beijing. It will only take you about 10 hours to finish the journey and the ticket fare is about CNY450. Of course, you could take a night T train, which takes you about 13.5 hours and CNY350/hard-sleeper.

Please search for the train schedule and ticket fare in detail on this page: https://www.travelchinaguide.com/china-trains/