Why did Maharaj suddenly start demanding so much Dakshina from Kashiram, even forcing him to go into debt?

This was a divine Leela orchestrated by Maharaj to aid his devotee's spiritual progress. Chapter 0 explains that Kashiram had developed a subtle pride, feeling upset when Maharaj didn't take Dakshina from him, which was an obstacle on his path. To remove this pride, Maharaj began a 'barrage' of demanding Dakshina, even instructing him to borrow money when his own ran out. This continued until Kashiram fully realized he didn't have the 'power to give.' Once this lesson was learned and his pride vanished, his financial condition began to improve again.