I would definitely retest as well.
The fact of the matter is that autoimmune disorders such as lupus or RA do put you at an increased risk of preeclampsia. So, if something has changed with your ANA level - you want to know about it 1. for the pregnancy and 2. for your health.
My test results have always come back fine and yet my peri still tells me that he won't be surprised if 20 years down the road, something emerges that explains why I might have gotten this disease.
I would really encourage a retest, if you're not comfortable asking your peri for it then I'd ask your PCP. Depending upon the results then I think you'll need to sit down and have a talk with your peri. If you don't feel like you're getting the care that you deserve, it never hurts for a 2nd opinion.
Let us know what you find out.