New reference letters are not required. They need your old reference letters, as your application is locked the day you submit it. Take your old reference letters, and all supporting documents that you submitted. The interview will revolve around your job. They will ask you where you studied, the nature of your education, as in what id you learn and then about your job. They will try and access that the duties you have in your reference letter is what you are actually doing. You should also take any IT returns, pay stubs if you have them. Or old IT returns will also be helpful.
Usually the interviews are called for applicants when the IRCC cannot verify their details, or if they called your employed, they could not verify the reference letters and that is all they want to check. So be confident and calm in your interview. It will not last for more than 15-20 minutes. Do not be aggressive, just answer their questions, and if you do not understand their question, ask them to repeat or re-phrase it.
You have your education and based on that your job. You are the one who has done it, just just want to cross check. Read your reference letters and make sure that all the job descriptions listed is what you actually do or did. Also, make sure you have the details of your company, as in where you work, the address, the email, you should remember that as you use it on a regular basis. This is all that they will look into.
At the end you can ask them if there is any supporting document that would need. Sometimes, they may just ask you to leave your Passport there and you will get it back with the visa. So do not worry, just go with confidence and let me know how it goes.
All the best!
