Since this word has okurigana (hiragana attached to the kanji) you know that it's probably going to be the kun'yomi reading.
Lucky for you, the kanji readings for transitive and intransitive verbs are almost always the same. Once you learn one, you know them both! This reading is the same as 延ばす.
Because of construction work, my usual running route has been extended.
The Tokyo Olympics were delayed to the following year, but they might get canceled.
I hate it when meetings are prolonged because of my boss.