I think sending her an email is a great idea. You can just ask her if she feels like catching up over lunch one day this fall. If you never hear back from her or if she's too busy, you'll have her answer. And it might be less pressure to do a seasonal lunch as opposed to one(s) around birthdays.

I have a friend who gets depressed every so often and when that happens, she won't initiate contact with anyone. I end up having to reach out to her all of the time, but we both have fun once I do that. It's just the way she can be and I've learned to not take it personally....
2Poodles Southeast PA
fine, med porosity, normal elasticity
Currently using the following 2 - 3 x/week:
Living Proof Perfect Hair Day suphate-free Poo, cone-free CO and styling treatment, plus KCCC