Hi bonsquared,
To start, studying for the GMAT now - far in advance of when you will actually "need" your Score - is a smart choice.
Many GMATers become too fixated on the 'implied level' of the questions that they're working on - instead of what really matters: defining WHY they're getting questions wrong and becoming more efficient at approaching the overall Exam. For example, if "your way" of approaching the Quant and Verbal sections leaves you open to making little mistakes, then you need to train to 'see' (and respond to) the GMAT in new ways. It's possible that you developed some 'bad habits' during your earlier studies that are keeping you from scoring higher; the type of Score that you're interested in requires a high level of 'precision', so you cannot afford to be missing out on a bunch of 'gettable' points. As an aside, it's also worth noting that just because a 3rd party describes a question as "700 level" does not necessarily make it so.
It's true that the At-home GMAT is a bit more 'palatable' of an option at this point because you are now allowed to use a physical notepad. However, many GMATers have reported technical issues with their Exams and the 'format' of the Test is "fixed" (Quant, then Verbal - with no break in-between, then an optional 5-minute break, then IR). Having to take Quant and Verbal in one sitting is challenging for most GMATers (especially if you've been taking your CATs with an 8-minute break between sections); from your last post, it's not clear if you were accounting for that aspect of the At-home Exam. If you want to take the At-home GMAT, then you will have to be really rigorous about how you take your CATs going forward (and take them in the exact same fashion in which you will have to take the At-home GMAT).
Thankfully, the GMAT is the same predictable Exam that it's always been, so you CAN train to score at a higher level.
1) Going forward, how many hours do you think you can consistently study each week?
GMAT assassins aren't born, they're made,
Rich