You do have an option other than stripping. It is a little difficult at first, but doable with a little practice. This will involve sanding, applying one or more coats of gel stain and then reapplying the poly finish coat.
First, do you have the original wood stain used on the windows? This is important as you will need to make a practice board that reflects the wood species, stain color and finish used.
Purchase a 3-4ft trim board that is the same type of wood as the windows, probably pine or fir. Now, stain and finish it the same as the windows. Allow this to dry for 3-4 days. Take this board with you to your local independent paint store and look at the available gel stain colors. See if the sales person will apply a little to the board so you can see how the stain changes the original color.
You won't be able to have the "perfect" color you want. But the original stain color can be changed or pushed into a new direction. The original stain color will affect the new gel stain color, its look or appearance. Having some small samples applied to the practice board will show this and help you determine the right gel stain for your needs.
Once you have a gel stain color, use the board for practice. Carefully sand the practice board with a fine sanding sponge, 180 grit, dull the surface. Now wipe off the dust and practice applying the gel stain with a very good quality white china bristle brush, 2 inch wide should work nicely. If you don't like how you are applying the stain, simply wipe it off with a clean rag and a little paint thinner before it dries and try again.
HINT- Use quick, short single direction strokes of the brush with a minimum of stain. Blending will be the most difficult part.
It is important to practice on this trim board before trying this technique on the actual windows. Once you have this down you can transform the color of your windows. The gel stain will need 2 days of drying time before applying the poly finish.
This same technique can be used on any stained and finished surface, including cabinets.