In my experience, the stripes fade if the plant is grown in low light. A brighter location brings them out again.

Thanks! I'll try that.

Not sure, does the "fragrans' (corn plant Dracaena) have stripes. I know the "massageana" does, as well does the "warneckii" and the "marginata" also.

As Karen pointed out, mostlikely cause is you are not giving the plant sufficient light. Dracaena can take less than good light. But a stronger light will make your plant grow stronger, with tougher leaves and better retention of moisture.

AT this time that can be difficult because the sun is just coming back north but will take a couple months yet before it gives plants what they like.
In this regard though, try to give the plant as much sun as you can by giving it exposures from the west, south....or if you have to, the east. A northern location just will not do the plant any good.

Dracaena is one of the plants that reacts to fluorine in the water. So try to let the water, if its out of the tap, sit for 24 - 48 hours prior to watering.
Fertilizer should ahve low ratio of phosphate. If superphosphate is part of any feeding program, withdraw that. Perlite too contains amounts of phoshurus and so should be not so much part of any potting soil you use for dracaena.

Not to disagree with anyone. But from my experience and seeing what happens to the ones at work, SUN is highly disliked by these plants. They burn easily, turn yellow, and even get bleached out.
I put mine in dappled sunlight, or in a high light area. Brite diffused sun is good too. Not in the direct day sun. Morning sun or late afternoon is also good. And they get that variegated look your asking for. I usually put these behind my full sun plants or under a tree. That is dappled sunlight.
In the winter, the new leaves that grow, are usually darker, with color stripe diminishing even if the sun from winter hits them.
They also grow awsome away from sunlight, or the window, but as you said, they loose that variegated look.

jeannie....(one more time) treated water contains FLUORIDE not fluorine. It does NOT evaporate out of a container of water if you leave it out. As a matter of fact, if you leave it out long enough, it (fluoride) becomes stronger as the water evaporates!

Also, perlite does not contain phosphorus (at least not that I know of). It can, however contain varying amounts of FLOURIDE, which can cause problems for sensitive plants.

I think that it's important to share information with others, but I do believe that that information should be at least somewhat correct.

I believe Flouride is water soluble Flourine

"Fluorine and its compounds are used in producing uranium (from the hexafluoride) and more than 100 commercial fluorochemicals, including many high-temperature plastics. Hydrofluoric acid etches glass of light bulbs. Fluorochlorohydrocarbons are extensively used in air conditioning and refrigeration.

The presence of fluorine as a soluble fluoride in drinking water to the extent of 2 ppm may cause mottled enamel in teeth when used by children acquiring permanent teeth; in smaller amounts, however, fluoride helps prevent dental cavities.

Elemental fluorine has been studied as a rocket propellant as it has an exceptionally high specific impulse value."

Here is a link that might be useful: Flourine

Sum mo info!

Here is a link that might be useful: Draceanas and Flouride