Only in extraordinary circumstances have students had to repay their financial aid. This would be the case if you were awarded and it was discovered that you filed a fraudulent financial aid application. Congratulations on your achievements at the university. You may check with your college office or academic department if there are any merit based scholarships available for which you can apply. The financial aid program in ISSS is primarily need-based.
Academic performance is only one criterion among others that is considered when making a decision.
You may want to consider applying for the Colonial Dames Scholarship. This is a prestigious award which is merit based and given to students who are demonstrating a commitment to their home country development. Also, please keep in mind that any financial aid awards from ISSS are benefits and not entitlements. I am an undergraduate and my GPA is below 2.5. You should certainly discuss your concerns and your situation with a financial aid adviser.