After saving a baseline the Earned Value metric BCWS shows the cost of the
work planned up to the specified status date. After posting progress
against the project, ACWP shows the amount you've actually spent up to that
date. Depending on whether you're asking for projected costs or actual
costs in your question, I would simply use the Earned Value tables and look
up first the BCWS and ACWP for Date1 and then the same for Date 2.
Subtracting BCWS1 from BCWS2 gives you the planned expenditure between the
two dates while subtracting ACWP1 from ACWP2 gives you the actual amount
you've spent between the two dates.