If you want to reuse a survey, but not want to lose the data (or keep the data separate), this can be done by making a copy of the original survey.
Once you have logged into Qualtrics, at the far right of the survey that you want to resue should be three little dots (it is a drop down menu). Click on that and select Copy Project. This will create an exact duplicate of the survey (without the data). So your data is still safe in the original survey, but you have a survey with all the same questions and options. If desired, you can make changes to the new survey as appropriate for your needs.