Ripley is currently being paid under her standard NXT contract, but she's also receiving bonus pay for any RAW events she appears on for the build to The Grandest Stage of Them All, according to Dave Meltzer on Wrestling Observer Radio. There's no word yet on what else Ripley will receive for actually working the big event in April.
On a related note, Meltzer stated that there are currently no plans for any other NXT title matches at WrestleMania 36. WWE currently has plans for 14 matches to be on the card and while plans could always change, Flair vs. Ripley is the only NXT title match on the card as of this week. It's possible that NXT Superstars will be used in the 7th Annual Andre the Giant Memorial Battle Royal or the 3rd Annual WrestleMania Women's Battle Royal, but the current direction has Ripley being the main NXT representative at WrestleMania 36.
The NXT roster will get their chance to shine during WrestleMania 36 Weekend at the big "Takeover: Tampa" event on Saturday, April 4 at the Amalie Arena.