Greetings Prabhat!

Hope you're doing great.

As you're the student of Delhi University then you must the knowing the details or you can either confirm from you college examination authority as well. Anyway, I'll try to explain the whole GE selection process. 

One of the advantages of the new 3 years integrated course erstwhile 4 years UGP is that(also called CBCS) it gives you the freedom to choose the kind of subject you want to study during you to stay at the college. As you've mentioned, English was your Generic elective during your first year hence it's advised to opt for English paper II in next semester to study the broad prospect and detail related to the subject. However, if you're not interested in English GE then you're free to choose any GE irrespective of your previous choice. So, yes you can choose Economics or any other GE subject as per your convenience. 

The marks awarded in CBCS system is semester oriented i.e once the marks have been allocated it cannot be reversed unless you practice redressal mechanism for paper correction or rechecking. Hence, whatever marks you've gained in English during your 1st semester will remain as it is. And if you choose Economic as your GE for next semester. In short, your marks depends upon the score you'll achieve during that semester ending examination. This is how the marks are calculated in the SGPA at the end of the 1st and 2nd semesters: 2 CORE, 1 AECC and 1 GE, so the maximum credits earned, would be 6+6+4+6.

Hope, your query has been resolved. Feel free to reach out in the comment section.

Have a great day ahead. :)

Cheers!