//If your issue is that the script is not continuing, you can use try and except instead.

try:
    tweet.retweet()
except tweepy.TweepError as e:
    print(e)
//In this case, you'll get the following message printed and will continue to retweet next tweets that are matching your search.

//Output: [{u'message': u'You have already retweeted this Tweet.', u'code': 327}]