After you reevaluate your goals and assumptions, you may find that the project scope has changed. For example, if you’ve cut or refined a goal, some or all of the tasks required to achieve it may no longer be necessary. On the other hand, if you’ve added a goal, you may need to add tasks.
But your goals don’t have to change in order for you to add or remove tasks from your project plan. A scan of your task list may reveal tasks that are redundant, trivial, or so large that they should be broken down into smaller tasks.