Raising the soil temperature sometimes stimulates the laying process. If she is just wandering around the bottom of the cage, then it is likely that something is not to her liking. It may the soil, the layout of the cage, noise, disturbance or the temperature. The latter is most often the case with Carpets but can apply to others.
This can be true of this time of year, particularly if the container sits on the ground or is put outside, when it can lose the heat it built up indoors and be quite cold. But even indoors a cold concrete floor can be deceptive. It would be unusual for a Veiled to be laying at this time of year in the wild but indoors the conditions are rather artificial anyway.
The soil mustn't be too hot which is why it is important to have a thermometer probe at the bottom of the soil. If the soil is no more than 24 to 25c then it is no warmer than the incubator.
There are many variables and this is but one suggestion. It may or may not be valid in this situation but is worth trying. There is nothing to lose if this is not the reason for not laying.
David