It´s implicit that the "would" that comes before "be the day" serves to the subsequent bits "she let her family" and "run away forever".
Same goes to "she left her family and ran away forever." One doesn´t need to say that "...she left her family and (she) ran away forever, let alone "(she would) ran away forever." Just one "she suffices", so just one "would" too, as they reffers to the same semantical level (same bit).
English is a very sophisticated language, one can easily underestimate it, though. Thus, it shorten and makes use of pratical usages (e.g. Omissions, metaphorical language, what you have.), in such a way that it assumes that the reader knows how to "fill the gaps", so they don´t elaborate some sentences in lenghty ways.
The very question you are making, shows that you are learning English, because we (that think in Portuguese or Spanish) are prolific writers, we try to explain everything. In a way we like the drama, they are terser in style.