改めて (aratamete) means “again” | MotiTan Japanese Dictionary

More examples

来週の予定を改めてお知らせします。rai shū no yo tei o arata me te o shi ra se shi ma su

I will inform you of next week's schedule again.

Describes doing something anew, with fresh attention or a deliberate return to it.

またmata: Indicates that an action or event happens again in ordinary usage.

以前にしたことを、意識してもう一度するさま。i zen ni shi ta ko to o i shiki shi te mō ichi do su ru sa ma

改めて (aratamete) is the adverbial form of 改める (aratameru, "to revise or renew"), formed with て (te), which connects the action with what follows.

In conversation, 改めて (aratamete) often signals that a point is being addressed again with special attention, so it sounds more deliberate than また (mata, "again").