Since I could not find any information on resealing the windshield, I thought I would post on the subject. My windshield sealant had a couple of small leaks on the top corners on each side. The rest of it was sunk in about a 1/4 of an inch. After extensive searching, I found out that this was the product originally used (AP Products 017-90893 Black Sikaflex 221 Sealant) available from Amazon. I ordered 3 tubes (1 was plenty). Here is the procedure that I used, it turned out perfect.
1. Use 2" wide blue painters tape and tape both sides of the existing seam. You can apply a double wide run if you are worried about getting some on your coach. Make sure you tape right up to the edge of the existing gap, but not into it.
2. Clean the existing sealant with a clean shop towel and acetone. Do not use paint thinner as it leaves a film or residue. Let dry.
3. Apply a bead of new sealant right over the old, applying approx. 20% more than actually needed to fill the gap.
4. With a clean putty knife, apply force down on the sealant, running in the direction of the seam. This will give you a fairly smooth seam top, with the residual pushed over to both sides. If there is a lot of residual, and you think it is going to get in the way, remove it with the putty knife. Let this set up for about 15 Minutes. I did this in 95 degree heat, so adjust accordingly. You want it to still be pliable.
5. Rip off a square sheet of household plastic wrap. Point at it, and wrap it smoothly around your forefinger and hand. You want the fingerprint of your fore finger to be as smooth as possible. Run your finger SIDEWAYS over the top of the bead in the direction of the seam. If you don't use your finger sideways, you will dig out some of the sealant in the wider gap areas.
6. Let this dry another 15 minutes or so, then pull off tape at a sharp right angle, not straight out. This helps keep the sealant edges to retain a clean edge.
7. If you got any sealant on your coach, remove it with acetone and a rag, being careful not to touch your new seam.
I forgot to mention a few things. Clean coach surface before you apply tape.
Wear disposable rubber gloves after you tape. Clean your tools with acetone before this stuff sets up.
Have everything you need ready, you don't want to be searching for the plastic wrap when this stuff is setting up.
You only have one shot at this. If you are not happy with your job, and it dries, you are stuck with it.