If there be any defect in form in any indictment, presentment or information, or if there shall appear to be any variance between the allegations therein and the evidence offered in proof thereof, the court may permit amendment of such indictment, presentment or information, at any time before the jury returns a verdict or the court finds the accused guilty or not guilty, provided the amendment does not change the nature or character of the offense charged. After any such amendment the accused shall be arraigned on the indictment, presentment or information as amended, and shall be allowed to plead anew thereto, if he so desires, and the trial shall proceed as if no amendment had been made; but if the court finds that such amendment operates as a surprise to the accused, he shall be entitled, upon request, to a continuance of the case for a reasonable time.