I didn't catch ya,can you repeat it/again? Pardon? What did you say just now? Excuse me? What did you say?

I didn't quite catch that. Could you repeat it? 我没有听清楚 = I didn't quite catch that. Other standard phrases: I beg your pardon? Could you say that again?

excuse me, could you say it again?

I did not hear it clearly, please repeat once more.

Beg your pardon?