In general, there is no statute of limitations on a claim for patent infringement. However, the Patent Act specifies a time limit on monetary relief for patent infringement claims – damages are available only for infringement that occurs within the six years prior to the filing of the complaint. In general, a voluntary dismissal (unless it’s the second such dismissal associated with that particular claim) just serves to wipe the slate clean – it is as if the suit was never filed. In that sense, it does not serve to toll any limitation period.
In the event the suit has been dismissed twice, the claim is most likely barred by res judicata as the second voluntary dismissal of an action operates as a dismissal with prejudice.
One other issue to point out on the topic of time limitations associated with patent infringement claims, while there is no formal statute of limitations, a defendant can still assert the affirmative defense of laches to prevent a patent holder from pursuing a claim, asserting that the delay in bringing suit is unreasonable, and the defendant will suffer material prejudice due to the delay. There is no formal time for the application of laches – it just depends on the situation.
If you are interested in more detail related to your specific situation it is best to speak with an attorney. Schedule a consultation with a Founders Legal Intellectual Property attorney