Your nails have gotten longer. Shouldn't you trim them?
「爪が伸びてきたね〜爪切りしようか!?」 = Your nails have gotten longer. Shouldn't you trim them?
「爪が伸びてきたから、爪切ろうね〜」= Since your nails have gotten longer, you should trim them.
になります。
Your nails have gotten pretty long, don't you think? ^^ How about we get them trimmed, huh?
satoさん
ご質問どうもありがとうございます。
下記の言い方ではいかがでしょうか。
Your nails have gotten pretty long, don't you think? ^^ How about we get them trimmed, huh?
爪が結構ながくなってきたんじゃない?爪切りしてもらったらどう?
ご参考にしていただければ幸いです。