I just baked the first batch of cookies and I found them to be too sweet to my liking. The remaining dough is sitting in the fridge right now and I was wondering if there is anything I could do to it to reduce its sweetness. These are the simple sugar cookies, btw.
It is almost impossible to reduce the sweetness of cookie dough once made, without further reducing the quality.
The closest you could come would be to create a second batch of cookie dough ingredients with reduced sugar, and combine it with your existing dough. However, it will be difficult to achieve good integration of the two batches, and even if you do, the extra working of the first batch from the mixing will create additional gluten, making tougher cookies.
In this case, you might want to try some sort of tart lemon glaze or perhaps a very bittersweet chocolate icing to compliment your cookies and reduce the impression of sweetness. On the other hand, except for butter, sugar cookies contain no expensive ingredients. It may not be worth trying to salvage this batch.
In the end, this is probably a lesson learned that your particular recipe is not to your liking as is. Next time, you will want to either reduce the sugar, or use another recipe.
A little suggestion, if I may.
Mix your remaining dough with no flour, some soft butter and corn flakes. Work the dough gently and form your biscuits as usual (try using a spoon to put them on the baking tray, since the high content of butter makes the dough very soft) and finally cook them - though a bit less than usual.
You'll get biscuits with a pleasant, sweet taste, but slightly salty and in proportion to the other ingredients there will be less sugar.
I often use this trick to save dishes with an excess of a certain ingredient.