my plant so far

my plant at home so far is not doing so good. however 4 small purple flowers have emerged from the main stalk. The roots are almost taking up the whole jar meaning it needs more room.So it could be the lack of space that is causing my plant top start dying. the plant has been on my window sill recieving lots of sunlight.The water however has not been changed since day one, so its been loving off the same water.The jar is almost empty so i had to fill it again because the plant has consumed most of the water throughout the 3 months ive had it. After the flowers came the plant started dying suggesting more water or nutrients where needed (and there was a lack of both).