Mantis molting

[Silkmoth]

Yes they can, antennae grow back in one to two molts. Legs take longer depending on severity. Arms usually not too well.
I am always nervous when my mantids molt. I've had some sad losses but not often. I have put the worst in the freeze if they cannot survive. Others are fine even though they look abit wonky.
Its important to make certain they have good footing as well as plenty space beneath when they hang.
I would not use vaseline. If it gets in their spericules they will die. Help them hang so thier wings will grow straight.

[JeffreH]

Good info Silkmoth - found this nice bit of literature to explain the physiology behind it:
Regeneration - It's All Fun And Games Even If Someone Loses A Limb

I stand corrected. I had based my previous response on literature and experience with the flies and wasps I work with; but failed to make the connection that those are holometablous insects who will only have the ability to lose any limb or antennae structure in their adult life stage. It would make sense for nymphal stages to have at least some degree of regeneration in subsequent moltings.