Why don't you ask your friend someday what she means by her statement -- not to criticize or judge her, but simply because you'd like to know what she believes? It might even open up an opportunity for you to share your own faith in Christ with her.
I suspect she's already given you some clues about what she means by this expression (which, incidentally, has become common today). For one thing, she's told you she isn't interested in "organized religion," by which she probably means any church or organized gathering. In other words, her "spirituality" is strictly a private matter (although she may enjoy being with others who share her views). I suspect she also sees "spirituality" as a feeling -- a feeling of being united with what she believes is a higher spiritual power.
The problem, however, is that sin is what separates us from God -- and her view of "spirituality" leaves no room for sin or forgiveness. This is why we need Christ, for He came to make our forgiveness possible through His death on the cross. The Bible says, "There is one God and one mediator between God and men, the man Christ Jesus" (1 Timothy 2:5).
Pray for your friend, and ask God to help you be a witness to her of Christ's love and peace -- both by your words and your life. In reality, she is searching for God -- and God's promise is true: "You will seek me and find me when you seek me with all your heart" (Jeremiah 29:13).