I assume you are using bitcoin qt. If you are not, please tell me which wallet you are using, and ignore the following.
To re-broadcast your tx, first get the raw transaction.
Open bitcoin-qt, click "Help, then click "Debug window" and click "Console".
Enter "getrawtransaction " (without the " and <>)
Copy the long strings and enter it on
http://blockchain.info/pushtxThanks for your help. Yes, I'm using bitcoin-qt.
Can I delete this tx if I don't want to rebroadcast and send it. I can't make sure whether the exchange can get the coin because I have generated a new address in the exchange platform.