Re: Losing/lost her interest
Just seems like you lost momentum. Happens to the best of us and it's fairly difficult to regain. Golden rule to prevent it is to make sure you escalate by using push/pull. There's plenty of material for you to look up about this.
As for recovery...there are a couple of options. New material (like you said) to engage her emotionally so she can feel again, that spark you had before.
You could also reveal a new layer of yourself. Open up a little to peak her interest, but maintain mystery so she wants to keep learning more about you. Become her rubiks cube she wants to solve, but never will. Only getting closer to a solution that will stay just out of her reach.
You could also try qualification. It's a great way to solidify any attraction you've built up with her by saying what you like about her other than her looks. This will make her feel special other than just another notch in your belt. Again, maintain mystery when you can, but don't lose momentum by letting it go stale. There is also plenty of material on qualification you could read up on. Hope this helps and good luck.
"All things are subject to interpretation. Whichever interpretation prevails at a given time is a function of power and not truth."