В общем, самый простой способ. В файле kernel/balance.pm есть такой код:
my $db = Db->sql(
"SELECT u.id, u.balance, u.limit_balance, (in1+in2+in3+in4+out1+out2+out3+out4) AS traf FROM users u ".
"LEFT JOIN users_trf t ON u.id=t.uid WHERE u.block_if_limit=1 AND u.balance<u.limit_balance AND u.state='on'"
);
меняешь на
my $db = Db->sql(
"SELECT u.id, u.balance, u.limit_balance, (in1+in2+in3+in4+out1+out2+out3+out4) AS traf FROM users u ".
"LEFT JOIN users_trf t ON u.id=t.uid WHERE u.block_if_limit=1 AND u.balance<u.limit_balance AND u.state='on'"
." AND day(now()) > 14"
);