Ditto on the refinance from 25 years to 15, it will save you hundreds of thousands, which goes right towards your retirement fund. I consulted for companys and on my own for over 20 years. Now I have a regular job with something that resembles a pension. At 15 years, I'll be 64 and will have just paid off my mortgage, so I'll have choices. I may "retire" then. I've been putting money in 401Ks and IRAs since I got out of school, looking back, I did pretty good, but should have stuffed a little more away. Biggest part of my net worth is the paper equity in my home, over 1/2 my net worth.
Use a simple calculator like this to figure out how much you'll have to sock away to retire.
http://www.banksite.com/calc/retire
In my case to retire in 15 years, live for 25 and have an annual cash flow of $60K, (not much 15 years from now, but you get the idea) I need to have about $1.7 million in the bank. You can go from there with interest rates, inflation, social security (hah!). But it gives you an idea of where you will need to be.