Yes, travelers can choose to switch their category after declaring one during the flight ticket purchasing process. Travelers are required by law to ensure that their activities fall under one of the legal categories of travel, but this includes the allowance for traveling under multiple categories on one trip. Since since travelers can only declare one category, they can select the one that they think best represents their activities at the time, but can then travel under that or any other category, or multiple.
For more help with answers to Cuba travel questions, feel free to message any of our local Cuban planners before you book. You can message one or several planners for free by clicking the messaging link on their profile.