Hello harmandeep

Sorry but according to the CBSE guidelines, students can appear for improvement exams the same year or for the previous year. Like for example if your 10th has completed this year i.e 2019 or last year i.e 2018, you can give improvement exam in both the cases. But if you want to give improvement exam for 2017 batch you are not allowed or eligible to do that, forget about 5 year.

Hope this helps :)