abed,
you have to apply for renewal before it expires. the application for renewal extends the validity of the card. in any case, some of the reasons for the renewal will be the number of hours a week and the continuity of the course. the perfect course would be spanish for foreigners offered by the official school of languages, 10 hours a week and the whole course from beginners to advanced lasts three years. passing each level would almost guarantee your place in the next course. you can add another language to assure approval since the minimum hours a week required is 15.
this student card allows you to study anything. so in addition to the above which will be easy for you to pass, you can also enrol and take exams for other courses, university among them. the entrace exams for university is very difficult, if you do not pass, you still get the student card renewal because you are a student of the official school of languages.
when you come here you must have an official copy (not originals) of your secondary education diploma and records, basic education diploma and records, translated to spanish and authenticated up to the spanish embassy, because you will have to apply for a their recognition as equivalent to secondary graduate and bachillerato diploma to be admitted for enrolment.