Why not throw her a surprise party? Pretend like you have no plans for her party, or that you will do something very small for her on a different date.
Plan BIG! You can either throw a surprise party at a ball room at a hotel, somebody's house or even as an outing surprise.
I have had several surprise parties thrown for me. I have no clue why, but for some reason people just love surprising their friends... or perhaps just me.
The latest surprise party that I had was at a friends house. The surprise started small, with about 10 friends, but then the party multiplied, the surprise prolonging throughout the night.
Another surprise party I had was when my bff took me out to a restaurant with her boyfriend.
When we got there, there were fifteen more of my friends sitting there! I was so surprised I could have cried.
They all pitched in together and bought me a really sweet digital camera, case, and photo albums.
They then took me to the movies, then out for coffee. Best surprise ever.
So why not make it special for her and give her a big surprise!