I wouldn't do anything suggested in the poll so I "nulled" my vote. Just keep patience, I don't know how long you've been trying for but trust me... its just a matter of time before you get it right! You mention them aborting... do you use a breeding net? How many fish and of which sex do you have? is it a species tank? Do you have any cover for them in their tank?
Hopefully with a bit more info we'll have you breeding platies in no time I'm moving this to the livebearers forum as well because you'll get more response there
I to gave a Null vote. Sorry but like William said patience is the key, crossed finger's& toe's help too. I would not change the feeding amounts or schedule could just stress the pair and cause more unwanted waiting.
Good Luck I'm sure you will have babies soon