Market assumptions are used in the goal and efficient frontier plans. When you open up a saved plan, you will be prompted to refresh the data. If you choose Yes, then the most recent market assumptions that you entered will be used to calculate the outcome. If you choose No, then the previous market assumptions will be used.
If you have deleted any accounts from the Accounts area, and those accounts were used in a plan, clicking Refresh will be expunge those accounts from the existing plan.