Magnum Contra used to be a very good funds in days when Sandeep sabarwal was fund manager. Since he left, fund hgas not shown outperformance. Many of it's peers are performing consistantly. I would suggest you to stop SIP in it and divert it for some other good funds like Reliance Regular Savings Equity, BSL Frontling Equity, DSPBR Top 100 & Franklin India Bluechip.
Also remember not to sell your existing Magnum Contra units immediately. Hold your units till they complete 1 year so as to avoid tax and exit loads.