Entity persitance inside Domain Events using a repository and Entity Framework?

Question

I am delving into domain events and need some advice about persisting updates to an entity for history reasons. My example deals with a User entity and Signing In:

    public class UserService
    {
        private UserRepository _repository;

        public UserService()
        {
            _repository = new UserRepository();
        }

        public User SignIn(string username, string password)
        {
            var user = _repository.FindByUsernameAndPassword(username, password);
            //As long as the found object is valid and an exception has not been thrown we can raise the event.
            user.LastLoginDate = DateTime.Now;
            user.SignIn();
            return user;
        }
    }

    public class User
    {
        public User(IEntityContract entityContract)
        {
            if (!entityContract.IsValid)
            {
                throw new EntityContractException;
            }
        }

        public Guid Id { get; set; }
        public string Username { get; set; }
        public string Password { get; set; }
        public DateTime LastLoginDate { get; set; }

        public void SignIn()
        {
            DomainEvent.Raise(new UserSignInEvent() {User = this});
        }
    }

    public class UserSignInEvent : IDomainEvent
    {
        public User User { get; set; }
    }


    public class UserSignInHandler : Handles<UserSignInEvent>
    {
        public void Handle(UserSignInEvent arguments)
        {
            //do the stuff
        }
    }

So where I have the do the stuff, I want to update the User object LastLoginDate and possibly log the date and time the user logged in for historical reasons. My question is, would I create a new instance of my repository and context to save the changes in the handler or pass something into the Event? This is what I am struggling with right now.