The Mexico international spent last year on loan at the Spanish club, netting 12 times in 29 appearances and president Jokin Aperribay hopes to bring the player back to San Sebastian.
Vela has been shipped out on loan four times since 2007 to sides such as Salamanca, Osasuna and West Brom with his career at the Emirates Stadium failing to ignite.Vela recently made it clear that he intends to leave Arsene Wenger's team and looks to be edging closer to a move to Spain.
Aperribay has claimed that discussions are progressing well, but admitted that nothing concrete has been agreed between the two clubs as of yet.
"We're getting somewhere, but there's nothing set in stone yet," he told AS.
"As the talks have evolved, I'm moderately optimistic, but there's no deal yet."