Agile project management is designed to handle continuous changes. The agile approach allows for flexibility and adaptability, making it well-suited to projects where the environment is dynamic and changes are frequent2. In an agile project, changes are not seen as disruptions but as opportunities for improvement1.
Therefore, the project manager should accommodate critical and urgent changes in the current iteration. This approach allows the team to respond to changes in a timely manner and ensures that the product or service being developed remains relevant and valuable1.
References: = Agile Change Management: Overview, Principles, Best Practices, 10 Steps to Introduce Change Management into Agile Projects

The project manager should review the lessons learned registers from the previous projects to identify the root causes of the failures, the best practices that worked, and the recommendations for improvement. This will help the project manager to avoid repeating the same mistakes, to apply the proven methods, and to enhance the project performance. The lessons learned registers are part of the organizational process assets that can be used as inputs for planning and executing the project12. References:
A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Sixth Edition, Chapter 4.4.3.1, page 112 Professional in Business Analysis (PMI-PBA) Examination Content Outline, Domain II: Planning, Task 7, page 10

The introduction of new requirements during the implementation phase can lead to scope creep, which may adversely affect the project's cost and schedule baselines. To manage this, establishing a proper governance structure is essential. This structure would include a change control board or similar entity to evaluate the impact of new requirements and make decisions on their inclusion in the project. This ensures that all changes are assessed for their implications on the project's objectives and resources before being approved1.
: = The need for a governance structure to manage changes and its role in maintaining project baselines is supported by best practices in project management as outlined in the PMBOK Guide2. Additionally, the Professional in Business Analysis (PMI-PBA) materials emphasize the importance of governance in change management and the role of business analysts in assessing the impact of changes34.