como lo vuelvas a hacer
si lo vuelves a hacer
si lo vuelves a hacer ---> in an imaginary world (space of events) where you 100% do this
como lo vuelvas a hacer ---> in the event you'd be doing this
si lo vuelves a hacer te arrestarán ---> mechanical description of consequence: Lo vuelves a hacer, te arrestan. No lo vuelves a hacer, no te arrestan. Si lo vuelves a hacer, te arrestan.
como
lo vuelvas a hacer te arrestarán ---> a warning: in the event
you do this you'll trigger a chain of events which
will lead you to this
You may think of "si" as powerful enough to create a branch of reality where things happen without really being happening (indicative because they happen) with all the branch being kind of an isolated reality -hence the mechanical aspect-. "Como" has not such a strength so it introduces what is more a comment within the previous reality and not an independent hypothetical reality. The eventual aspect of that, the warning aspect and its discouraging intention (don't do it) are all three carried by subjunctive.
You know, Spanish verbal system: powerful, flexible ... difficult