I do feel bad for Lana as well. She has been so excited, and also great to fans during this whole filming and release process of the movie. However, if you look at the film and compare Jubilee's scenes to the previous movies... Lana, even with her scenes being cut, shows up more than the first three Jubilee appearances combined. Her total screentime is actually more, I believe, than Jubilee's X2 appearance WITH the deleted museum power scene. Almost as much as X1 Iceman, and More than X2 Kitty, Colossus, and Siryn.
However, the mall scenes have been announced to be included in the DVD release. There is a montage of the four teens walking around the mall, in the food court, nightcrawler breakdancing, Jubilee using her powers in the arcade, and them going to a record store.
I'm assuming a few of her other scenes were reduced, too, and will hopefully be on the DVD.
Seeing how popular Lana has become and has been on all of the interviews/shows... hopefully it will help her career and also give her a big chance at returning for the next X-Film or New Mutants.