I bought a cornplant about 1 1/2 yrs ago. It has been slowly dying since day one! The leaves are "wavy" and have brown tips, then they gradually turn yellow, then turn brown and crispy and I have to end up cutting them off. It has already lost it's top 3 bunches of leaves. Now the bottom leaves are doing the same. I am going to end up with just the bare canes. The ladies at the plant nursery from where I bought the plant were very adimant that I only water once a month at the absolute most. I water with distilled water most of the time. This is my favorite plant and it also holds sentimental value. How can I save this plant?

First of all buying a corn plant from a nursery such as Home Depot or Walmarts you will be buying a grade B plant. What that means is.....its not quite the florist quality of one that is purchased from a regular grower. It may have root problems that being an adverage person you can't tell. The fragrans cane (dark green leaves) is the harder of the canes. While it can can go almost a month without water, an every two week schedule would be better. That is providing you have it in adquate light. Brown tips are cause from illregular waterings, and yellow leaves would tell me the light is too low.
These type of plants have very fine almost like hair like for roots, so over watering will drowned your plant. To avoid that situation water until the water runs out then leave it alone for two weeks. You may not be able to save your plant. Once they start to deteriorate, its too late usually. Sorry, hope this helps you some for the future.