Exchange student with X2, Shanghai febr. 26, 2018 + 180 days. Question about a 144 hour visa.

My Danish daughter is right now staying at a university in Shanghai as an exchange student. She has a X2 running from february 26th and 180 days ahead.

She has a return fly ticket back to Denmark from Shanghai on 31th of July.

BUT! During July she wants to go for sightseeing and Holiday outside China, but still wants to fly home from Shanghai on 31th of July. Because she wants to pick up her suitcases at her dorm at the university.

How and where can she reply for a 144 hour free transit, so she can be sure to be let into Shanghai again and stay a few days before flying home? And if that is not the right type of entry permit, what kind of one-extra-entry-visa would be right, and where to reply for that?

Thanks!