This approach is one of the best and most proven methods to re-initiate contact with your ex. 

1 Trial Message every 3 to 4 weeks to gauge where she’s at emotionally and if she’s open to meeting up. There are two types of Trial Messages: 

Trial Message without CTA "Hey [Name], it's been a while. Hope you're doing well." 

Trial Message with CTA "Hey [Name], it's been a while. How have you been?" 

If she replies with a question (for example, asking how you are), it's a sign she's open to further conversation. Your next message could be, "I'm good, thanks. Been really busy with work. I was thinking about inviting you for a quick coffee, just to catch up and clear the air. Who knows, maybe we could be friends again. No pressure if you're not up for it." If there’s no reply or no question, repeat the process in 3–5 weeks.