You need to transfer from Foshan to Guangzhou first and then take train T170 14:00/08:56 (the next day) to Shanghai from Guangzhou railway station. It will cost about CNY650.00 if you take the soft sleeper.

For the flights from Guangzhou to Shanghai, there are many choices both to Shanghai PVG airport and Shanghai Hongqiao airport. The air ticket is CNY1300 per person including the
tax and the airport construction fee. Of course, sometimes
you can get a better discount. Hope it is helpful.