code needed to reduce % risk

Here is my code that I use to trade with money mgmt....

NormalizeDouble Lots = accountequity() * PercentRisk * 0.001/StopLoss


I want to add code that will reduce the value of Lots as I acquire losses for that particular currency pair and vice versa.....increase Lots for that particular currency pair as I acquire wins. It needs to be symbol dependent and not just equity based because I trade different pairs. Any help would be appreciated.