to change food that has been dried back into its original form by adding water

The powdered milk/egg can be reconstituted by adding water. 奶／鸡蛋粉可以加水复原成牛奶／鸡蛋。

to change an organization so that it has a different form

The Health Education Council has been reconstituted as the Health Education Authority. 健康教育委员会已经改组为健康教育局。