If you find that your icing, fondant, or sugarpaste is hard or dry then simply add some Trex or some other alternative vegetable fat to it, although a rule of thumb with this is less is definitely more! Make sure you use it in stages and slowly otherwise you run the risk of adding too much and making a mess. Trex in moderation will soften and loosen sugarpaste/icing/fondant making it pliable and easier to use, all you need to do is rub a little between your hands and then knead the icing/fondant/sugarpaste with your hands, which in turn will soften and restore it.
Tip: Trex or vegetable fat is a great tool if you are using your icing/fondant/sugarpaste in a Sugarcraft gun. The Trex acts as a lubricant in the barrel and helps form the shapes as the icing/fondant/sugarpaste slides easier through the barrel allowing the shape making process much easier.