"What happened to us a year ago was very different to the situation we find ourselves in now and we are far better prepared this time," said Wenger.
"We prepared for Van Persie to leave and recruited early with Lukas Podolski and Olivier Giroud and we have added to that strength with Santi Carzola.
"I believe we have a much stronger squad now than we had a year ago and that is why I was comfortable with the decision to let Song go."
However, Wenger is open to adding more player to his squad before the end of the summer transfer window.
"I have many options in midfield and feel we are well covered," said the Frenchman. "We may also bring one more into the squad in this position."
Arsenal are back in Premier League action this weekend when they take on Stoke City on Sunday.