Hi Sreerag,

If you take a drop, your new percentage will allow you to be eligible for appearing in the KEAM of 2020. There is no upper age limit for candidates, so there should be no issue with your passing year. 

Just for your reference, the passing marks required to appear for the KEAM are - 

50% in Mathematics individually

50% in Physics, Mathematics and Chemistry put together

If you can get in under the management quota in private self financing engineering colleges, you only need 45% combined (Physics+Mathematics+Chemistry) to be eligible. 

If you do take a drop, I would advise you to check the eligibility criteria once more in 2020 before going in for an admission through the KEAM.