My gym has very limited dumbells(upto 50lbs), therefore, my one arm dumbell row is not that much of a challenge to me anymore.Is there any other excercise that I can do that will give me that V-tapered shape to my back?

P.S.My other back excercise's include,lat pulldowns,seated cable row.

What you should try to do is a the cable one arm row. Check it out on the exchange list. It is a great exercise as long as you have a cable machine with a low pulley system.