Forex increase is due to variation of foreign currency (As the article posted says). It is due to rise and fall of foreign currency against the dollar. Only if the dollar keep dropping every week for 1 year you will get $300billion. Is that likely ?
But Rupee IS dropping..... so your imports will cost more. India subsidises oil. You use US$ to buy oil. So you still pay more in Rupee. India should have drop the oil subsidy during the good times. Drop it now, the government will fall. Dont drop it and it will drain your forex reserve. Its a double edge sword.