I got kidney transplant in 2010, last month it was rejected, had 10 plasma xchange n 2 dose of rituximab injection, now its normal, when I can get concive?

Fairly risky. Pregnancy is possible for a female kidney transplant recipient whose kidney function is good and stable. Yet, it is still considered a high risk pregnancy for both the mother and the fetus. Although you may be capable of conceiving now, it would be unwise to do so until your function stablizes at a good level for at least 6 - 12 months.
See below. My suggestion is to consult your transplant nephrologist, however my opinion would be to wait for a stable renal function, before conception and calculation of chances of further rejection.Pregnancy is a strain on kidneys and anti rejection medications maybe contraindicated.Ultimately the decision would be yours.