I AM DOING expression analysis of multiple genes from same cDNA sample and since there are many genes I will perform qPCR over few days9 in a weekend), do i have to prepare actin for each time i do PCR.
You need to measure the reference genes only once in a cDNA sample. But if you use several runs/plates in which the same genes (from different samples) are measured, you will need a run/plate calibrator.