My ex doesn’t want to get back with me after leading me on

So I recently started talking to my ex again 2 months ago. Everything was going fine. She would flirt and just be her old self. Recently, something has changed. She stopped showing lots of attention and doesn’t speak to me as often. Is she leading me on?

Sounds like she thinks you're just exes that are now friends. She's moved on, whether she's with someone else or not. If she's not making passes or saying she wants you back, then backpedaling, you are not being led on. You're simply confusing friendship for flirtation. If you're not interested in being just friends, then you need to move on too.