What sodas have no [or a harmless amount of] citric acid?!
Limit soda to an occasional treat, no matter how much she loves it, because you love her. That said, many fruit-flavored sodas have less of the citric acid. Root beer is low, too, I understand. Stay away from lemon-lime and any other citrus sodas, and from colas.
Using a straw helps keep soda off the teeth. Having a good drink of water after drinking soda helps to wash away the acid.