For example
hypothetically lets say @ 25700 we have 25500 pe at 100*200 = 20000, now when the index goes up by 200 points we may have 25500 at 50 rs. so instead of planning to buy another 200 @ 50 = 10000, to make it an average of 75, why not ;buy 25700 pe 100 at 100= 10000, so if the index reverses the 27700 will recover faster and we may even get greater returns from it.