Do I need to check into the hotel again?

Legal analysis: generally not needed. If you don't get your room back before noon 12 the next day, the hotel will consider you as your continued stay and you don't need to register again. When you check in at the hotel, you must check in. Ordinary tourists don't need to register with their ID cards if they don't stay.

Legal basis: Measures for the Administration of Public Security in Hotel Industry

Article 6 A hotel must register for receiving passengers' accommodation. At the time of registration, the passenger's identity documents shall be checked and truthfully registered according to the prescribed items. To receive accommodation from overseas tourists, an accommodation registration form shall also be submitted to the local public security organ within 24 hours.