Since I'm switching to active duty Army from WI Army National Guard, can I retake my ASVAB so that I can reclassify?

I was able to retake my ASVAB in a similar situation. I joined the AD in 98, in 2004 I joined the National Guard and was told I was not eligible to retake the test. Then when I joined the active duty in 2006 I was told I had to retake the test because of how old my score was. But, it wasn't a matter of choice.
However, a good work around is that you can go to an education center and take the ASVAB if you are near any military base.

Find your local on base education centre. They will be able to administer the ASVAB.
Just know that whatever score you receive will be your new score. You won't be able to keep the highest of the two.

Have you already got a conditional release from your unit?

You should be able to.