Hey ShanShan!
Your new increase in exercise is a really positive step! Keep up with that. As for the soda "addiction," one thing I do is to dilute the soda with plain sparkling water. You may think that sounds yucky--and at first it will taste diluted. But as you get used to it, you'll find that it's just fine--and you save at least half the calories.
Of course, drinking plain water is a good idea too! I often add a wedge of lemon or lime to the water--helps make it better tasting.
Do you have a specific weight loss goal? Let us know.
Good luck!
Jay