Papa John’s International Inc.’s founder John Schnatter regrets resigning as chairman after using a racial slur during a training session and believes the company’s board mishandled the situation by pushing him aside without an investigation, according to people familiar with his thinking. The Papa John’s board declined to comment, according to spokesman Peter Collins. Papa John’s shares fell 1 percent on Tuesday to $50.88 at 9:35 a.m. in New York.