Unfortunately, plants are 'generating' organisms, not 'regenerating', like animals. That means they cannot regenerate cells in the same spatial positions, so cannot heal themselves. We often use the terms regeneration/regenerating when we speak of plants, which is inaccurate in a technical sense, but perfectly useful in a practical sense. This inability to grow new cells in the same spatial planes is applicable not only to the damaged foliage, which is just a symptom, but possibly to the underlying cause of the symptom if it is related to root damage.

If this is a recent photo, at some point you can cut the plant back to below the green leaves and wait for it to back-bud. It will. The new foliage will emerge in pristine condition, which puts the pressure on you to keep it that way. ;-) It would be much better if you did this next Jun, when day length is waxing, but if you live in the southern part of the state, you could probably do it now with nothing but a slowed recovery to be concerned about.

You need to get your watering and fertilizing under control. It's a near certainty that your spoiled foliage is related to one or the other, or both of these issues. A soil that drains well and doesn't support a significant layer of sogginess at the bottom of the pots (which do have drain holes - yes?) will always offer you the easiest route to getting the most out of your plants. It also takes much of the guesswork out of watering and fertilizing.

I'll leave a link that covers some of the basics and will help you to avoid habits and conditions that have the most potential to limit your plant. If, after you read it you want to learn more, let me know and I'll link you to a thread that explains a concept I think is extremely important for anyone growing in containers to understand.

Al

Here is a link that might be useful: Covering the bases ....

Besides Al's advice, look inside the vase of the leaves. Mealybug are known to invade D. Corn Plants.

Check for white or brown clusters/bumps. Also check for sticky residue. Toni

MN - Just for the sake of clarity - there might be a possibility there are mealybugs somewhere on the plant, and regular examinations for pests are always a good idea, but the spoiled foliage in your picture isn't caused by mealybug unless by chance it might be root mealies. Damage so clearly limited to leaf tips and margins is virtually certain to be related to the plant's inability to move enough water to take care of the plant's transpirational needs - a damaged or impaired root system.

Al