Checking your copper sulphate bath can be done by yourself.
Try to find the book “Electroforming” written by Leslie Curtis.
Leslie is (was?) teaching at the School of Jewellery, Birmingham, GB
at the plating department.
Published by A & C, London, GB
In this book are some ways described how to check your copper
It depends on the volume of your bath. When it’s a small amount, you
can also consider to get rid of your old bath (in a proper way!) and
start with a fresh one. Some times it’s not worth the trouble to
check and regulate a small quantity of liquid.