Expansion of C drive for refreshing the PC

I have an HP laptop having Windows 8 inbuilt. There were so many problems with it that I called up HP Customer care and asked for the solutions. All they could help is to tell me to refresh my PC. I was shocked by their response but as they were the only ray of hope for me, I tried to refresh my PC as per their instructions. When I clicked on the "Refresh PC" button, it shows a pop up message that it need 27 GB more space in C drive to perform this operation. I have allocated 100 GB to my C drive and it's almost 93 GB data in it. I tried to empty some space but all I could manage is 88 GB. I don't want to remove the softwares in it as it will effect my business. I need these softwares on daily basis. I asked the customer support about expanding the space allocation of C drive, but they denied to tell anything as it is not in their guidelines to tell user about changing the memory allocations of PC. They said it could crash the whole hard drive.
