I haven't seen you for a while. I miss you.
How are you doing? I haven't seen you for an age!
How are you doing? It's been a long time since we last met, hasn't it?
It's been a while since we last met.
I haven't seen one of these in forever.
It is [has been] a long time since I saw you last.
I haven't seen you for ages. Do you remember when I saw you last?
It is a long time since I saw you last.
めっちゃ久しぶりやん。
It's been so long! Finally we have met.
It's been a while since we last met.