Converting Monthly Subscription to Annual

Hi team,  I want to convert my monthly subscription to annual. I want to avail the annual discount subscription. I have active monthly subscription w.e.f 22-04-2020. Is it possible that my monthly subscription can be converted to annually by subtracting the amount that I have already paid. I mean 138 dollar ( annual subscription) less 36 dollar.  I will make extra payment of 102 dollar for annual subscription. Is it possible?.