It's actually pretty iffy if the referral will work with a sub that was cancelled (I know, I tried).
In theory, I believe, go into your cancelled account, go I think to your referral page and get your referral link. Copy this, and sign out of your account. Close the page, and make sure your are out of Popsugar. Open new window. Post link you had copies, hit enter. Click boxes, monthly box, and buy. It should have you put in any coupons if you have them, so put in your Rue code. Make sure it confirms full discount. Create account with new email address. Check out. This should get you the October box, but it may or may not get you the referral. You may have to email them, and they may say no.
Cancel this account at some point so you don't get Nov. Do this again with a new email and your other rue code in November, or when Popsugar says October is sold out.
I'm fairly sure you're getting September, as it didn't switch to October until the 1st. Check your account sub page, it may tell you. Otherwise, email them ASAP to see if they can change it.