The interviewers want details on what you work on. So have examples of your work ready to discuss in detail. They also want to see how you think, so be able to think conceptually. Understand foundational concepts of languages and systems you use, and if you are going for a more senior position, be able to explain advanced topics.
The best way to prepare for an interview is to take refresher courses, and review commonly-asked interview questions. Accept an interview and do your best. See where you need to brush up, and don't feel demoralized because you need to project confidence. Sometimes, you will not be selected and it has nothing to do with your answers. Accept that, and have the courage to move on.
You will get better with each and every interview, as opposed to staying in a stagnant position. It is true that engineers are life-long learners, so keep up these habits even in the next role.
I wish you the best of luck!