Hey Erina,
I think i remember your story now, and looking at your previous posts, it seems that the reason was that you "did not provide legal proof regarding marriage barrier". Since you are getting married in 3 months, then it makes sense for your application to be refused in the conjugal category - as it's for people that can not get married, no matter what. I'm not saying that it's good that your application has been refused, and I understand that it must be sad and frustrating for you of course. I'm just saying that from CIC's point of view, it's logical.
So in your case, your best bet is probably to re-apply once you get married. The good point is that the VO did not reject your application because they think that your relationship is not genuine, or did not have enough proofs about the relationship. If they only mentioned the "legal barrier to marriage", once you get married, the obstacle is eliminated... so I would say - re-apply. Waiting for a date of appeal etc will be really long, and you won't qualify for an appeal in the conjugal category because you'll be married by then.... so you have now 3 months to put together the new application. You can use the same proofs as you have had before, and add the continuous relationship with your partner. As well, as you're getting married in 3 months, you have time to get everything ready, and as soon as you're married, you get the certificate and you can send the application.
Most likely, if you have been approved the first time for sponsorship, then the first stage will be easy and quick. Second stage will take a while, but maybe because a few things have been already assessed, you will get a fast approval in second stage as well.
Good luck,
Sweden