It likes to dry out between waterings - are you over-watering it?

Run a leaf through your index finger and thumb - does it feel 'gritty' or 'fuzzy'? If so, that's white leaf mold - wipe all the leaves down, remove any with brown on them, stop watering unless the soil is dry to your first knuckle.

Is it getting enough light?

Did you acclimate it from the window to the outdoors? They are very sensitive to climate change.

Nancy,

You have nice little DR, and I can see that your plant is growing new leaves, if stem is hard I do not see any problem here! If there are no bugs or fungus visible let it be. It is common for DR to defoliate during winter, go dormant, and resume growth in the spring or just drop leaves at any time when conditions change (heat on/off humidity etc). I would re-pot at same level or lift it a bit if there is enough caudex to do so. If you pot it deeper parts of the caudex already acclimated to being above soil level will go under and I see no benefit from it.
Good luck, Aggie