All the requirements so the new revision should be checked as audit criteria. If the laboratory is already accredited to ISO 17025:2005, then the major changes in the 2017 version need to be focussed on. For example Clause 8.5 Addressing Risks and Opportunities. Questions must be asked to seek objective evidence. Two example are “Did the laboratory consider risks and opportunities associated with laboratory activities in order to: Give assurance that the management system can achieve its intended results?” and “Does the laboratory plan and take actions to address these risks and opportunities?”
Your Accreditation Assessment Body would have policies, guidelines and checklists for transition requirements. For example a laboratory would need to ensure that effective implementation of all ISO 17025:2017 requirements have been assessed through the audit programme and gaps closed.
Have a look at the ISO 17025 document template: Internal Audit Checklist, which is an appendix to the main document, Internal Audit Procedure. The checklist has a list of questions required to ensure the management system is implemented and maintained. It includes more than 100 questions to ensure each requirement of the ISO 17025 standard is implemented and maintained within the Laboratory Quality Management System, and includes the ability for you to add additional questions to suit additional needs. It is available at https://advisera.com/17025academy/documentation/internal-audit-checklist/