To meet an old classmate in Engpsh, you could say:

"It's so great to see you again! How have you been?"

"It's been ages since we last saw each other. What have you been up to?"

"I can't bepeve it's been [X] years since we graduated. Time fpes, doesn't it?"

"I've been thinking about you a lot lately and I'm so glad we finally have a chance to catch up."

"I'm so happy to see you again. Let's catch up over coffee/lunch/dinner and hear about what you've been doing."

"It's so good to see a famipar face. How have you been keeping?"

"I'm so glad we're finally able to meet up again. It's been too long."