You do not have to ask God for anything. As you know he knows your wants and needs. God has given us a free will to ask for and do as we want. The choices are ours. Yes God knows what we need and he also knows what you will ask for. He also knows if you decide to stop asking for things since he knows what you need. I myself thank God for what he has provided me and what he will provide me. About the only thing I ask for is forgiveness.
Click here for some more information on the subject.
More information can be found in the links below.
http://www.bible.org/page.php?page_id=2888
http://www.discoverymagazine.com/digger/d00dd/d0007dd.html
http://www.normalbobsmith.com/askgod/
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