Changing the water is fine. This should be done while keeping the roots safe from damage. Hold the flowers and stems carefully while pouring out the water and refill with regular tap water. The bulbs need to stay upright without being damaged by the plastic “needles” of the tray.
It is very important not to over-water the bulbs. Roots should be kept in water and avoid dipping (splashing) the bulbs in water when moving the vase.
Make sure to keep the roots under water, but never to submerge the bulbs like you see in the picture below where the water level is too high. With a water level like that, chances are high the bulbs will drown and go bad.