Yes, you can dilute the sample and get buy for a few days while you wait on you refills. Another option is to use an OTO kit (no dilution necessary) and the color chart here to help you read 'off the scale' colors. http://pool9.net/oto-chart/

As far as the fitting the bottles in the case issue, you can always just buy larger bottles and just refill your smaller ones. I'm pretty sure that 4-oz bottles are sold and maybe some other sizes as well. I'm not sure what all is available size-wise on Amazon, but one place we have used before is www.spspools-spas.com.

Something you can do if you are running out of your R-0871 to help stretch it out a little longer is to drop the water sample size to 5ml, and then each drop will be 1 ppm, instead of 0.5 ppm.