Hi I hope you can help me I have a painted block foundation that is parged and needs some repair after I remove the loose paint and parge will I be able to reparge over some of the area that still has paint on it and what should I do to prepare the surface to accept the new parge

Power wash the foundation where you need to reparge and get all the loose paint off. You can try a concrete bonding agent that you brush on before you parge.
Do this is a small area and see if it parging adheres for you. If not, you'll have to attach wire mesh/lathe to the foundation, put on a "scratch" coat (a first coat of mortar and as it dries you scratch it w/ a trowel or stick to put lines on it so the final coat would adhere). Then apply your final coat and float to so its smooth.