If you told her that you would talk to her tomorrow, then call her.
You have to be aware that when you ask a girl to the beach that this may put some of her insecurities front and center. Insecurities like unwanted body hair, love handles, scars, etc. She may also suspect that you're a perv that just wants to see her in a bathing suit. I think for this reason, I've been rejected on the beach date. Is this the first date? The couple times I was rejected on the beach date was on a first date and second date. The second date chick actually turned into an LTR and we ended up going to the beach often later in the relationship. Some girls just need to feel comfortable with you before going to the beach.
On the other hand, I've had a few first time and second time dates to the beach. So I think it just varies with the girls comfortability level with the dude and her handling of her own body insecurities.
Call her and see if she offers a different date idea or if she rejects the beach you should offer a different date venue. If she rejects the new offer then move on, she's not interested. Good luck!
