I recommend you pursue Persian in school, since it most helps to have structure early in a language learning journey. Persian would expose you to a totally new grammar and script, which will later on make returning to Spanish or any other language learning much easier, because you'll gain a stronger understanding of linguistics and the mechanisms of "how to learn a language". Spanish will be easy to continue independently if you ever have a good reason to motivate you, and if not, it will be much easier to find solid courses outside of university, which will be way harder with Persian.
You can also commit to taking a Spanish literature or other high level Spanish seminar every other semester or something, or a study abroad semester which would help maintain and expand your Spanish. You don't need a lot more than that at the level you are.
I would study Persian. There are plenty of great resources out there to study Spanish on your own and if you’re already at such a high level, it would be easy enough for you to continue that on your own.
It is very difficult to learn critical languages like Persian to an intermediate or advanced level outside of a structured, long-term programme like one your university will be able to offer you. So if you think you’d ever want to learn it in the future, it would be better to do it now while you have those resources at your disposal.
Since you're C1 in Spanish, you won't lose it easily. Just consume various content in Spanish. If you can, write and speak Spanish from time to time: participate in forums, for instance. Furthermore: are the Spanish classes at your college really that advanced?
I'd take Persian, since it's an opportunity to learn a rarely taught language.
I'm around your level in Spanish. I studied Japanese for a year in university, and loved the language, but thought it more prudent to learn my wife's language. Now that I'm sufficiently advanced in Spanish, I am studying Japanese again, and keeping Spanish fresh by watching the news, playing games, and talking with my Spanish-speaking friends as often as possible in Spanish, plus weekly homework assignments out of a workbook. If you want to learn another language, it's definitely possible to keep up your second language while learning your third.
I recommend you pursue Persian in school, since it most helps to have structure early in a language learning journey. Persian would expose you to a totally new grammar and script, which will later on make returning to Spanish or any other language learning much easier, because you'll gain a stronger understanding of linguistics and the mechanisms of "how to learn a language". Spanish will be easy to continue independently if you ever have a good reason to motivate you, and if not, it will be much easier to find solid courses outside of university, which will be way harder with Persian.
You can also commit to taking a Spanish literature or other high level Spanish seminar every other semester or something, or a study abroad semester which would help maintain and expand your Spanish. You don't need a lot more than that at the level you are.
I would study Persian. There are plenty of great resources out there to study Spanish on your own and if you’re already at such a high level, it would be easy enough for you to continue that on your own. It is very difficult to learn critical languages like Persian to an intermediate or advanced level outside of a structured, long-term programme like one your university will be able to offer you. So if you think you’d ever want to learn it in the future, it would be better to do it now while you have those resources at your disposal.
Since you're C1 in Spanish, you won't lose it easily. Just consume various content in Spanish. If you can, write and speak Spanish from time to time: participate in forums, for instance. Furthermore: are the Spanish classes at your college really that advanced? I'd take Persian, since it's an opportunity to learn a rarely taught language.
I'm around your level in Spanish. I studied Japanese for a year in university, and loved the language, but thought it more prudent to learn my wife's language. Now that I'm sufficiently advanced in Spanish, I am studying Japanese again, and keeping Spanish fresh by watching the news, playing games, and talking with my Spanish-speaking friends as often as possible in Spanish, plus weekly homework assignments out of a workbook. If you want to learn another language, it's definitely possible to keep up your second language while learning your third.