One way of discouraging people to open multiple accounts and stopping trading in the account which has just touched small profits is to have graded refund system:
0-5 % on the capital------20 % brokerage refund
5-10 % ------ 50 % refund
10- 20 % ------- 75 % refund
20-30 % ------- 100 % refund
30-50 % -------150 % refund
50 % and above ------- 200 % refund.....
for 150% and 200 % you are not going out of pocket...as these cases will be less and they will be financed by the savings you make on the lower slabs...this will encourage people to trade on the same account till the end and achieve high return figure and claim more refunds rather than just qualify for refund and stop.....
Just call it performance incentive scheme and your critics will be silent, as you are encouraging traders to do well and 100 % and above refund only people making 20 % and above are getting...so no free lunch, it is encouragement for performance....
Something on above lines , slabs and % ages may vary .....lower and higher respectively the better ...
Smart_trade