Step 1: Parts
A spray bottle
A very flexible tube that is the same diameter as the tube in the sprayer.
A couple of nuts
Step 2: Assembly
Using the straight tube as a reference, cut some flexible tube to about an inch longer than the current tube. This will allow it to reach anywhere in the tube.
Take the nuts and screw them onto the flexible tube. You want a tight fit. You can see that I'm using a wrench to do this. It won't work if they are sliding up and down the new tube.
Once you have all the nuts attached, you can insert the other end of the flexible tube back into the top of the sprayer.
That's it! Go take your new and improved sprayer and get all those hard to reach places!