I see this being spoken of a lot. That you should 'next' her. Now I'm not into advocating being her texting/phone buddy, but for me the best success I've had over the years just comes from being charismatic and high energy with everyone.

Often times, if you keep that up you'll find she becomes single a year later and shows high interest again. Or she comes back around to you.

The second you start to sulk and ignore her/cut interest, you're basically just cementing that will never be anything.