Reset System.Lazy

In a business class I have :

 class Employee{

      public Employee() {
          m_Manager = new Lazy<Manager>( () => return myRepository.GetManager(ManagerId); );
      }
      public int ManagerId { get; set;}
      private Lazy<Manager> m_Manager;
      public Manager Manager { 
          get {
               return m_Manager.Value;
          }
      }
 }

This is working correctly, the custom repository is called only if accessing the Manager property. Now I want to "reset" my manager property if the ManagerId changed. How to do that ?

I can do :

 class Employee{

      public Employee() {
          m_Manager = new Lazy<Manager>( () => return myRepository.GetManager(ManagerId); );
      }
      private int m_ManagerId;
      public int ManagerId { 
          get { return m_ManagerId;}
          set { 
               if(m_ManagerId != value)
               {
                    m_ManagerId = value;
                    m_Manager = new Lazy<Manager>( () => return myRepository.GetManager(ManagerId); );
               }
          }
      }
      private Lazy<Manager> m_Manager;
      public Manager Manager { 
          get {
               return m_Manager.Value;
          }
      }
 }

Is there a cleaner way to do that ? Isn't there a m_Manager.Reset() or something like this ?