We meet again!：
また会いましたね！→すこしカジュアル
Hello again!：またこんにちは！（また会ったね！）→カジュアル
We run into each other a lot, don't we?
私たちよく出くわしますね。
→上の２つよりすこしフォーマルなニュアンスになります。
I think I've seen you here before. Do you come very often?
So we meet again!
The first expression is formal and not very intrusive.
It would not make the person feel uncomfortable.
This would be considered and innocent and friendly question.
"So we meet again" is very causal and somewhat funny.
I would use this expression with someone that I've talked with before.
一つ目は、フォーマルで控えめな言い方です。
相手は、悪意のないフレンドリーな質問だと思うでしょう。
"So we meet again" はとてもカジュアルでちょっと面白いです。
私ならこの表現は、すでに話したことのある人に対して使います。
1. I noticed you working out here a few times. Are you getting any fitter?
2. Excuse me, do you know what time the gym closes this evening?
3. Hi, I just want to ask you, can you see my abs - or am I still fat?
1. This is quite a casual question which would require the correct amount of smiling and friendly intonation.
2. This is more formal and is a random question about opening hours. Obviously, if this person is open for further discussion then you will see the signals.
3. Here you are asking for someone's advice as you want to know if your abdominal muscles are visible on your stomach. This is kind of funny. Probably informal :-)
Hello, I've noticed you here before! How do you do?
"How do you do?" is a traditional and formal greeting in English. By adding in a few other words it makes it into something more casual.
"We meet again!" is a common phrase we use when we keep coincidentally seeing someone over and over again. It can be used when seeing a person twice or more without intentially agreeing beforehand to meet.
"How do you do?"
（お元気ですか？）
という表現は伝統的かつフォーマルな英語の挨拶です。他の言葉を幾つか添えることでよりカジュアルな響きを持たせることができます。
"We meet again!"
（また会いましたね。）
これは偶然の誰かに出会うことが続いている場合に良く使われる表現です。
例えば、特に会う約束をした訳でもないのに誰かに2回とかそれ以上出会ったりしたケースに使えます。
You could say something like
" I run into you all the time"
or
"I find you here often".
a more formal way might be
"we encounter each other often here!"
or
" I often see you here".
下記のように言うことが出来るでしょう。
"I run into you all the time"
（とてもよく会いますね。）
"I find you here often"
（あなたをよくここで見かけます。）
ややフォーマルな言い方としては下記があります。
"We encounter each other often here!"
（こちらでよくお会いしますね。）
" I often see you here".
（あなたをこちらでよくお見かけします。）
We can simply say that we, "meet," again if it's someone we see often at the same place. We can also use the verb, "to cross paths," or, "to run into," to say that it's someone that we see often at the same place.
英会話講師のKOGACHIです(^^)/
おっしゃられている内容は、
I think I've seen you here before.
「ここで以前にあなたを見かけたことがあると思います」
または
We often see each other here, don't we?
「よくここで会いますよね？」
のように表現できると思いますm(__)m
以上ですm(_)m
少しでも参考になれば幸いです(#^^#)
お困りの時は、いつでも気軽にご質問ください(^0^)/
★★どうぞよろしくお願いもうしあげます★★
see you soon♪
日本 
アメリカ合衆国 
イギリス 
