Answer: Since you have had your Corn Plant (Dracaena fragrans) for a long time you probably already know to keep it in a spot with medium light and away from hot dry drafts such as that from a heat vent or radiator. Watering depends to some extent on how much light the plant receives; the brighter the spot the more water it will need to keep it moist. Warmer temperatures will also increase the need for water, while a cooler room will lower it. These plants do not require a wet soil by any means, so if kept in a low light situation or a very cool room then water only sparingly. These plants grow fairly slowly so they don't need too much fertilizer, a dilute application about once a month should be enough. There are several possible gebneral causes for the problem you describe: an overly dry atmosphere and/or dry soil, overwatering, or insects.
While it is possible that the repotting (perhaps some root damage, a larger pot or a different type of soil mix) has changed the plant's watering needs, based on your description I suspect your plant has spider mites. These tiny pests peak in mid-winter and thrive under the low humidity found in most homes during the winter. Examine it closely in a bright light and look for fine webbing, especially on the underside of the leaves. You may also find that the leaves show a paler stippled look before they turn brown. You can treat these by washing the plant regularly with a strong spray of water or by using insecticidal soap according to the label instructions. Increasing the humidity around the plant will also help.
Good luck with your plant!
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