I found one free online test, but I don't know the quality:
http://www.humanmetrics.com/cgi-win/JTypes1.htm
You can take the test at the following sites for a fee:
http://www.capt.org/take-mbti-assessment/mbti.htm
http://www.knowyourtype.com/order.html
I'm sure you'd get better quality results with the assistance the second two site provide....but if you've already taken the test before, the free one might serve your purposes.
As far as personality changing...I've changed definitely. When I first took the test, I was pushing the outer limits of Introversion, but I'm sure I've moved toward the middle a good bit. Maturing as an individual partly involves developing our weaker traits. You can also test differently from day to day depending on your mood. In fact, when I took the test years ago, the lady who worked with me had me come back and take it again because she thought my Perceiving/Judging results showed some possible error.