I wouldn't drop to standard, because your marks won't improve. I doubt they would take 'pity' on you, (for want of a better word) and mark you higher on the same standard of work just because you are in a lower class. Keep in adv at least for this year, and I agree with everyone else;
Talk to the teacher and find out what you are doing wrong. Start out from the basics, make sure you have good structure to your essay.
I use the formula:
Value:
Technique:
Example (quote):
Meaning:
Effect:
For every paragraph, about 1 sentence-ish on each.
If you have a shit teacher try other sources, a tutor is good if you have the money, but if not there are other ways.
Once you have the basics down, having strong concept and structure, THEN start improving your vocabulary, and hence sophistication.
With practise youll improve for yr 12 ^^ Ask your teacher for extra practise essays and have them mark them (if you have time that is..). And if you can get your hands on some other essays, read them. If you have friends who are getting good marks, ask if you could read them and compare theirs to yours, see what is different.
But dont drop yet.