A Kansai-dialect informal word meaning 'once more' or 'again'. Used in casual speech.
すみません、もっぺん言うてくれる？
Excuse me, could you say that again?
写真、もっぺん撮ってくれへん？今度は目を開けて。
Can you take the photo again? This time open your eyes.
そのレポートはもっぺん見直しときや。
Look over that report once more.