I'm not sure what you mean. Do you mean that the transaction is not yet confirmed? In this case, there are two options.
1) If the original transaction was replaceable (depending on your wallet, this can be set with a check box), you can use RBF (Replace By Fee).
2) If you can not use RBF, you can try doubling the original spend at a significantly higher fee to convince Miner to complete the second transaction before the first transaction, invalidating the first transaction.
If your transaction has already been confirmed, you will need the secret key of the old generated address to create a new transaction from the old address to the new address.