For reasons that I don’t fully understand, the Lord sometimes allows us to experience great need and then He doesn’t answer until we have prayed “enough”.  It’s probably not so important that we know why this is true, but it’s very important that we know that it is true.  If we didn’t catch on, we might quit praying too early, falsely believing that God was simply unresponsive to our need.  One example of this kind of repeated request that received a remarkable answer is found in John 4. 

So Jesus came again to Cana of Galilee where He had made the water wine. And there was a certain nobleman whose son was sick at Capernaum. When he heard that Jesus had come out of Judea into Galilee, he went to Him and implored Him to come down and heal his son, for he was at the point of death.  Then Jesus said to him, ‘Unless you people see signs and wonders, you will by no means believe.'”

Christ’s response might have discouraged a less determined person from asking – but this man was desperate.

The nobleman said to Him, ‘Sir, come down before my child dies!’

Jesus said to him, ‘Go your way; your son lives.’ So the man believed the word that Jesus spoke to him, and he went his way.  And as he was now going down, his servants met him and told him, saying, ‘Your son lives!’

Then he inquired of them the hour when he got better. And they said to him, ‘Yesterday at the seventh hour the fever left him.’ So the father knew that it was at the same hour in which Jesus said to him, ‘Your son lives.’ And he himself believed, and his whole household.”   – John 4:46-53 (NKJV)

So the lesson we learn is: Keep asking!