[Leia doesn't respond right away, instead searching his expression and seeing how far she wants to go with this questioning. because she knows he's being stubborn about this because he doesn't want to talk about it, and she's made her side of the conversation abundantly clear. Or she thinks it's clear enough, anyway. After a moment or two, she sighs before responding.]

If it comes up again, we'll discuss it then. But whatever you're worried about, I don't want you to be. I love you, Han.

[And to punctuate that point, she leans in to kiss his lips. It's not as if him being insecure about her feelings about him hasn't happened before, and she does have a feeling it won't be the last. So, if just words won't make her point, maybe actions will help.]