Well, this would depend on the event, the skill, and the level. If she does not fully complete the trick before falling, such as a bhs on beam where she misses her feet, then she does not recieve credit for the skill--it would be beneficial to do the skill again. If they to do recieve credit for the skill and are only deducted for the fall, then no need to repeat the skill. Also, the belief in repeating skills varries from coach to coach. Also, many upper level gymnasts know what their requirements are for their routines, so if they know that they failed to complete their jump series on beam, they would most likely know to add two jumps somewhere in their routine. Do you have a particular level and event/skill in mind?
Another question along those same lines: My dd is level 4 and still doesn't have her ROBHS. She does a nice round-off but doesn't have the BHS with it yet. I know she'll get points for the RO, get a deduction for the value of the BHS but will she also get more of a deduction for leaving out a skill completely? Thanks!
I believe the deduction for omitting a skill is 8 tenths, but it might have gone up--I can't remember exactly. While, the deduction for falling is at least 5 tenths. So, to answer your question, yes the score for completely omitting a required skill is more than taking a fall for it.