Has the cardiologist asked you to monitor resting respiration rate? That is something that pet owners can do. There is a canine CHF yahoo group where there are discussions about these things in great detail.
Do you have urinalysis run as well as blood chemistry to check kidney function? Kidney failure will show up in urinalysis long before it shows up in blood chemistry. By the time that BUN and creatinine are elevated, kidneys are only working about 25%. But a low urine specific gravity gives you an advance warning and you can make some dietary changes, etc. I have actually purchased a digital refractometer so that I can measure USG at home.