Love these comments LOL. Here is what I do.

When he says he is going to cum here are some options I use:
Cum for me (as you already do) - you can simply change this up in itself, cum inside me baby, cum for your dirty girl, etc.

"give it to me"

"I wanna feel it inside me" or "I want to feel it all over me" - depends where is going to cum and then reference that.

if he is cumming inside; "fill me up" or "fill me up with that warm cum baby", etc.

Moaning is great too, sometimes that is all you need :)

I don't think it is weird to say the same things. it is totally in the moment and natural, I doubt he cares if you repeat yourself!