The 19-year-old made his senior debut during a month-long spell at Selhurst Park.
Egan figured twice for the Npower Championship side and has come back to Wearside keen to press on.
"I feel like I've come back a better player," Egan, who is the captain of the Republic of Ireland's Under-19 side, told safc.com.
"I played two games and benefited from those as well as training with the first team.
"It was a good experience and I feel better for it.
"My aim now is to try and kick on, impress the manager and get into his plans. We will see what the rest of the season has in store."