It took about a month and a half after we began dating for the first girl's ex to reconnect with her. And I really liked her (and he is an abusive asshole, she deserves so much better). Man did that suck. With the second girl, it took about three and a half weeks for her guy to come back (he was supposed to have left the freaking country!). I really liked her too. The third girl, it took her ex literally two days to contact her after our first date (and they had been apart for over five years!).
So, I appear to be getting better at this. Not only can I get you your boyfriend back within a few days, I can bring him back from incredibly unlikely circumstances. Have you been pining over an ex? Want him to give you a call? Perhaps he moved to Russia 12 years ago, got married, has 7 children, and you haven't heard from him since. No problem! One dinner and a movie with me and he'll likely be waiting on your doorstep when I drop you off.
Now, I haven't had a chance to properly test this, but I suspect that my skill works much better if we sleep together. Now, this might not be absolutely necessary, but you do really want to see your ex again right? Why risk it.