Hi Snowe
One thing I know about IRNs is that the relationship is always evolving. It can be distressing if it's not evolving in the direction that you want it to. However, the positive side of this is that it's not stuck there and it can evolve in the other direction. I suggest that for a while you keep trying to interact with your bird using food rewards (like you've mentioned) to get her to want to do what you want her to do. What I'm saying is that for now EVERY time you go to interact with your bird (when you walk up to the cage, when you open the cage door, etc.), do it with treats. Once you've one her back again, you may be able to back off with the treats. Make sure the treats are really small so that she won't fill up on them too quickly.
The lunging is definitely trying to communicate something to you. It could be that she is scared but it could also be excitement, boredom, etc. For example, when my husband walks into the room our Janey will generally lunge at one of the hanging toys in her cage because she is excited.
If you haven't done it already, I would also recommend increasing the amount of food she gets through foraging. I found this really helpful with our Janey. Here are some links on foraging:
http://www.indianringneck.com/forum/vie ... 01&p=69400
http://www.indianringneck.com/forum/vie ... =4&t=13466
http://www.parrotenrichment.com/ - this site has some free ebooks to download
Good luck, let us know how you get on.
Ellie.