Can my 700cc high profile saline implants be refilled with 100 or more cc?

It is certainly possible to overfill saline breast implants past the  manufacturer's recommended range.  It is possible to utilize your own (existing) breast implants, assuming that doing so can be done carefully/safely and that doing so will suffice when it comes to achieving your desired outcome. You may find the attached link, dedicated to "larger" breast augmentation surgery concerns helpful. Best wishes.

Yes, your saline impants can be refilled. Many times this can be done under a local anesthesia in office visit.There afre several ways to get the fake look-either with overfilled saline implants, custom XL silicone implants or XL tissue custom expanders.It depends really on what cc size to want to get.
You can think of a saline implant as a balloon. The manufacturer recommends an overfill of about 20cc but they have been shown to be able to be filled much more than that. They do start loosing their shape and can significantly distort the appearance of your breasts. 
 I do overfill espcially since the FDA has restricted saline and silicone implants to a maximum saline shell size of 800cc and maximum silicone size of 800cc. I do not know why that number was picked arbitrarily. 
So, I do do breast reconstructions greater than that with XL tissue expanders which do pride a greater diameter and projection and upper pole fullness and allow the size to be adjusted either up or down. Also, the shell of the saline implants are very thin and can dreflate more easily. You may want to visit my site below which explains everything, esp for XL sizes which is my specialty, either initially or revisional surgery.