1. There you go, you put the bad-mouth on others.

Question

2. There you go again, you put the bad-mouth on others.

3. There you go. You're always forgetting things.
4. There you go again. You're always forgetting things.

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Do we have to use 'again' or not? Are both okay? Which one is commonly used? Otherwise, are both different in meaning?

Answer 1

See your other post about these.

Keeping the word "again" in there is a good idea for this particular expression.

Most of the time "there you go" is a phrasing meaning "you're right" or something similar.