Expiring provisional patent

The short answer is NO. In order to preserve your date priority, which is usually the prime number one reason for filing a provisional application, you must file a US non-provisional application or a PCT before the one year anniversary of your provisional application filing date. If you miss the deadline, you're out. Some people will tell you that you can file an application later without claiming the priority back to the provisional application, but there are at least two problems with such strategy: 1) you lose your provisional application filing date priority; and 2) even if you choose to forego the priority, somewhere along the line, the provisional application may come to light, in which case you may run the risk of having committed fraud on the patent office by not disclosing the provisional application. I would check with a patent professional who might be more knowledgeable as to whether such a question has been litigated and decided. In addition, things may even be worse if you choose to pursue foreign patents - if you file a non-provisional or PCT application after the one-year time frame, you may likewise get into litigation in, for example, Europe, and if somehow the provisional application gets disclosed and the fact that you did not file your PCT application within one year from the filing of the provisional application, but you filed it first or within one year of filing your later-filed non-provisional, your foreign patent rights may be invalidated.