Start by submitting your site to Google. It will not be instant. As your new site starts getting more hits, and your old one gets less/none, your new site will climb higher.
From a buddy of mine:
I went on google and got 3 wrong websites for Philadelphia Regional Anti War Network. One was SOA watch, one was from one of our marches 2 years ago, and one was from the Friends Center.
Is there a way to get them removed?
How can we get our new one up there?

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