This is tricky. Your intentions are good — but those student loans belong to your children. Your retirement belongs to YOU! And your goal should be to pay down your mortgage and personal and home equity debt before you retire. I’m guessing you have no idea how much it will cost you and your wife to live during retirement. But as a “for example” Fidelity just estimated that a couple retiring at 65 can expect to spend $285,000 in uncovered healthcare costs over their retirement!
You need to reconsider your perspective. Your children have student loans. Those come with obligations and some benefits. The rates are high, but they can pay as they earn, more each year. But this is THEIR responsibility, not yours! Now is the time to make that clear to them.
Yes, refi your house and put your home equity loan into the balance – and don’t take out a loan longer than 15 years. With a bit of luck and extra money you can pay it down early. And then, you might want to gift your children some money each year if you keep working, to pay down some of the principal on their loans.