I don't have any advice for you about what to do, but--
You can call Vanguard directly and have your retirement funds rolled over to a personal IRA at Vanguard. That would help in two ways: you probably are having to pay a small additional administrative fee from your funds while they are in your former employers plan. You won't have to pay this additional fee once the funds are rolled over.
More importantly, once you roll this amount (more than $1 million) over to Vanguard, you'll be a Flagship member. You'll get access for free to financial planning, including some help determining what level of risk you are comfortable with and some suggestions for how to invest your money. You could decide to keep your money in the same fund that it's in now, but at least you'll have some help making the decision.
But call Vanguard and discuss with them what you have and what you want to do. They were very helpful to us.
PS You could also call Fidelity or other places--they can all help you roll your funds over, regardless of them being with Vanguard now.