Last time they didn't, surprisingly. I'd imagine most of that money will go to the general election nominee and senate/congress candidates.
Another problem for them is that turnout is significantly higher during a general election, making it harder to drown candidates. Hillary, like Obama in 2008 and 2012, is going to have a rising tide effect on multiple dem candidates. Whereas if you spend a shit ton of money in a midterm election with low turnout you can gain more seats.
I'd use the money to convince state congressman to split electoral college votes in blue states dominated by republican legislatures/governors. Michigan and Pennsylvania almost did it last year but backed down due to fear of voter anger. Perhaps a big ass check would convince them to go through with it; PA now has a democrat governor so it wouldn't work, but maybe Michigan? The main reason this is a blue state is because of the big cities. If you split the EC votes based on districts it would have been possible for Romney to receive more EC votes than Obama in 2012 for instance.
It's a dangerous plan that would certainly backfire two years later when angry voters shitcan the congressman who supported such a heist...but if it managed to elect a republican president wouldn't it be worth it to sacrifice some state legislators?