It was unusual for Jesus to inquire about the results of His ministry as He did in verse 23 of Mark 8:22-25.  It was even more unusual that Jesus laid hands on this man a second time.  This is the only example in the New Testament where Jesus had to minister to any need more than once to affect a total healing.

Many people request things from God and then look at their circumstances to see if God answered their prayer.  That is walking by sight and not by faith.  If they can't "see" God's answer, then they pray again asking for the same thing.  This is not the way Jesus taught us to pray and receive.  We can be sure that Jesus didn't lay hands on this man a second time because He thought His Father hadn't heard Him the first the time.  Since the man received partial sight, it is evident that God's healing power was at work in him. Jesus was not petitioning His Father again for healing.

Through His spirit, Jesus knew that unbelief was hindering a perfect manifestation of God's power in this man, and He simply gave him another dose of the anointing power of God.  Satan may hinder, but cannot overcome someone who continues resisting him.  Believe that you received when you prayed and continue to apply the power of God.  Press in such a degree that you can confront anything that is contrary to what you have asked and overcome it. 

Perseverance in prayer is the key to overcoming Satan - not God.