Are there any limits to how many times you can visit a doctor's office for preventive care under obamacare?

Specific Health Plan: You need to read the fine print of your specific health plan that you decide to purchase. While preventative care is mandated under the aca, it's not unlimited. Most plans limit preventative care to one visit per year for a check up, and then age specific visits (like for a pap or colonoscopy if you're the right age). It will be different for young children - most plans cover multiple visits/year.

Probably: While few us really understand fully the new health care law, preventative care usually refers to items such an annual exams, paps, mammograms, etc. These are things which are done to catch disease early before there are any symptoms. Most other doctor visits are for managing, evaluating or treating specific conditions, and these are generally not considered preventative care.