When you pray for something do you pray until it’s answered or pray just once and forget about it until it’s answered?

Some think that there is not any reason to pray because God already knows what we need (Matthew 6:8).  However the Bible tells us to pray to God and let Him know our desires.  I believe that Jesus has given us some guidelines to follow when we pray.  First we need to be humble about it (Luke 18:9-14).  Second we need to make sure that we are praying for God’s will, not our own (1 John 5:14-15).  And finally we need to be persistent and keep praying until it is answered (Luke 18:1-8).  The problem with many is that they don’t get the answer that they want so they think that God didn’t answer their prayer.  God will always answer our prayers and we should keep praying over a matter until He does.  “Pray without ceasing.” 1 Thessalonians 5:17