The bar change from flat to riser will raise the level of your hands by the amount of the rise, and depending on the sweep of your current bars vs the riser bars, may put your hands at a different angle. The question is do you want that change, i.e. to be a bit more upright? And maybe have your hands at a new angle? If you still have some spacers above your stem, you could put them below the stem and raise your bars by that amount, for free. You could also change your stem to a higher rise and raise your hands as well. If you really want the riser bars, there are quite a few choices across the budget spectrum if you'll look around, try googling bicycle riser bars.