If additional time/expenses are submitted after an Invoice has been created, it's possible to press the "Refresh Invoice Lines Transactions" button and it update the Project-based lines. The same doesn't happen with Product-based lines.

When an Invoice has been created that contains products as well as project lines it should take any changes made to the pricing of Project Contract Products when the "Refresh Invoice Lines Transactions" button is pressed. Currently the only way to recalculate Product-based lines is to delete the entire Invoice and recreate it.