PERSONALLY, if you can handle one more season in DV, I would sell everyone but the minimum needed to win the league. Strip down to the bone, and make as much money as possible (you SHOULD be able to make 100k a week. Play your A team in the cup, probably making about 150-200k. Then, when in Season 20 you promote to DIV, you should have at least 2 million in the bank. you can buy a very good DIV team for 1 million (3 starters, since you have two already, plus back ups) and up grade your arena. Keep in mind you get a 300k promotion bonus, plus extra attendance.
In fact, I'd even up grade your arena now, just to get it done. YOu probably want it between 6-10 thousand, to be able to make between 100 and 130k. Trust me, I did the same thing as you, but with out the season in DIV. Look at me now, I'm in 2nd place my first season in DIV.
By season 20, your trainees should be in great shape, and ready to compete with DIV bigs (10-35k in salary). good luck!