1. RBF - If you had this option (Replace By Fee) enabled prior to sending the transaction, you can increase the transaction fee.
2. CPFP - If the transaction you sent, had a change output (another output aside from the one you intended to send), you can use this option (Child Pays For Parent). In simple words, you have to pay a high fee that covers both transactions. You can read the following thread, in order to understand it in better details: https://bitcointalk.org/index.php?topic=2610402.0