So, I'm going to cut down on my sugar for a month

[323]

You could always go with a zero calorie soda. Like pepsi max is pretty darn good for being a "diet" soda.
As for other options check out your water section. Most the time they'll have flavored but unsweetened or lightly sweetened fizzy water.

Ooh that's a good idea, those flavored waters are great.

Tea.

Another awesome idea, I should go buy some. I actually just ran out.