Patent attorneys are asked this question numerous times, so I thought of addressing it here. Yes, you may refile a provisional application as long as you have not publicly disclosed your invention and understand that you will not be able to take advantage of the previous provisional filing date.
Let’s get into the details:
A provisional application is a temporary filing that holds your spot in a time based queue called the priority date, which, in case of provisional applications, is the filing date. This is the date the USPTO recognizes as your invention date. In other words, anyone who came up with a similar idea as yours after your invention’s priority date will have inferior rights to you – in other words, they won’t be able to obtain a patent on the exact idea of your invention (as long as you pursue a non-provisional patent application claiming priority from the provisional filing).
And before we address the main question, another important aspect to be aware of is that provisional patent applications are held in confidence at the USPTO. This means that unless you publicly disclose your invention or the fact that you have filed a provisional application, no one will know about its existence. So refiling a provisional application simply means discarding the previous application and filing a new one, and being awarded with a new priority date.
And this brings us to the main question — what happens if you refile a provisional application? Since a refiled provisional application will be awarded a new priority date, if anyone filed an application disclosing a similar invention after your first (original) provisional filing, but before the second (refiled) provisional filing, that person now holds superior rights over the invention than you.
And to make things a little more complicated (since nothing is simple in patent law) also keep in mind, statutorily, you have one year from publicly disclosing your invention to file a patent application. Thus, you may not be able to refile the provisional application if the refiling happens to be more than one year after your public disclosure. What constitutes as public disclosure is a complicated subject by itself. For example, a casual conversation regarding your invention with your best friend over dinner can be considered as a public disclosure (depending on what was disclosed).
To summarize: Yes, you may refile a provisional application, but your invention’s priority date will change and this may affect your innovative rights.