“Staying in touch” suggests keeping some contact that isn’t too intensive. He hasn’t spoken English regularly for 30 years but he stays in touch with the language by watching American movies in their original version. I recommend staying in touch with the languages you learn in school. Otherwise you’ll forget them completely.

Yes, the sentence sounds OK, but I don't think it says what you mean to say. How about - "I recommend ongoing practice with the language. That will increase your fluency."

Thanks, Sandanee

Yes, I also think you are right...If we want to improve our English knowledge we must practice hard to gain more...