Why is it dry? Did you use too much flour again? But why would you throw it away? If you made the recipe correctly, with more or less the right quantities of ingredients, just add moisture. Add a little water, perhaps a half-teaspoon at a time, and mix until you're satisfied with the consistency. You might also add some or more vanilla extract, or you could use egg white for the added moisture.

Another question, however, is whether the dough is really dry, or is it just stiff because it has a lot of cold butter or shortening in it - perhaps something you might not confront in the heat of summer? If that's the case, the shortening will melt in the oven and most likely produce the cookie you're expecting. If dough isn't able to absorb all the flour in the mixing bowl, however, then it is probably too dry and needs moisture.

If, on the other hand, you added way too much flour, your options are to increase the other ingredients proportionately or throw out the batter. A cookie with too much flour will be crumbly, dry in the mouth, and probably tasting of raw flour. Who wants that?