Mistrials are generally not covered by the double jeopardy clause. If a judge dismisses the case or concludes the trial without deciding the facts in the defendant's favor (for example, by dismissing the case on procedural grounds), the case is a mistrial and may normally be retried. Furthermore, if a jury cannot reach a verdict, the judge may declare a mistrial and order a retrial as was addressed in United States v. Josef Perez, 22 U.S. 579 (1824). When the defendant moves for a mistrial, there is no bar to retrial, even if the prosecutor or judge caused the error that forms the basis of the motion. An exception exists, however, where the prosecutor or judge has acted in bad faith. In Oregon v. Kennedy, 456 U.S. 667 (1982), the Supreme Court held that ''only where the governmental conduct in question is intended to 'goad' the defendant into moving for a mistrial may a defendant raise the bar of double jeopardy to a second trial after having succeeded in aborting the first on his own motion.''

Is it true that can a prosecutor refile charges after a mistrial?
yes