A sequel to this fic is now online and in progress, titled "This Platinum Crown"
Of course, I can't link it here due to FFN formatting, but it is under my author page here on FFN, just like TBNE and everything else.
This Platinum Crown
Description: After the time-looped events of The Best Night Ever, Rarity's relationship with Prince Blueblood seemed to be a fairy tale come true. Perhaps so, but it was a fairy tale soon cut short. Her dreams and future position quickly earn her the attention of powerful enemies. Only one mare can bear the Platinum Crown of the Duchy of Canterlot and be heiress to it's secrets and magics. The future of Equestria may well depend on that one mare being Rarity Unicorn.