[22M] How to structure a conversation with my partner [19F] about rebuilding our 4-year relationship before I move abroad for the summer.

My partner [19F] and I [22M] have been together for 4 years. Recently, we separated because I felt I needed space to experience single life in my early twenties. I have since realized that this lifestyle is completely unfulfilling, and my ultimate goal is to rebuild our relationship and future together.
We maintained contact and she was reaching out to me until very recently. However, I just had a conversation with her best friend, who informed me that my partner is currently trying to distance herself to move on and might be seeing someone else casually.

I am leaving for a Work & Travel program in the US in exactly one month, which adds a tight deadline to this situation. I will be away for the entire summer.
I am struggling with how to approach our next interaction. I want to lay my cards on the table, communicate my realization, and show my desire to commit fully, but I need to do so respectfully given her current stance and my upcoming departure.
How can I effectively structure a conversation to communicate my change of heart and intentions to her before my flight? I am looking for specific communication strategies on how to initiate this dialogue and express my commitment without overwhelming her.

TL;DR: [22M] Separated from my [19F] partner of 4 years to experience single life. I realized I want to commit to her, but I leave for the US in a month and she is currently distancing herself. How can I structure a conversation to effectively express my intentions before I leave?