Hi, I am Dr. Peter and would like to help.
1- Any nasal or eye discharge?
2- Is she eating and drinking?
She was eating well until this morning when she refused her food, but she does that from time to time. She does not seem distressed.
Common causes for excessive sneezing would include allergies, nasal or sinuses (infections, foreign body, polyps, etc.) problems, environmental allergens, etc. In a puppy foreign body (debri in nasal passages) or something in the environment triggering the sneezing would be common causes. What you can do is apply a drop of water in each nostril to clear out her nasal passages. In addition, if you take a hot shower take her in the bath room with you and allow her to breath the vapor for 5 minutes; this will hydrate and help clear the nasal passages. If the sneezing continues after doing the above, follow up with your veterinarian.
If you have additional questions I will be glad to answer them.