I don't recommend re-canning commercially canned food unless it is something you are using in a recipe that you are going to can. However, I found 2 different answers to this question. I am giving both answers here FYI. I believe the folks at All American are speaking of fruits only. It is not usually cost efficient to re-can anything.
The first one is from the All American Canner Manual FAQ'sQ. When canned or frozen fruits are bought in large containers, is it possible to can them in smaller containers?
A. Any canned or frozen fruit may be heated through, packed, and processed the same length of time as recommended for freshly prepared food. This canned food may be of lower quality than if it had been canned when fresh.
Listed below is what the National Center for Home Food Preservation has to say about re-canning food
Is it safe to jar already canned food?
Often people think that they can save money by buying larger containers of canned food, transferring the contents (or leftovers from the first use) to smaller jars and re-processing it. Others wonder if this is a way to save leftovers from any size can for a longer time than they will keep in the refrigerator.
There are several problems with these practices:
(1) We have no safe tested processes to do this. In some cases, the way the heat is distributed throughout the jar during canning will be very different if you start with already canned/cooked food than with fresh. Excessively softened foods will pack more tightly into a jar, or arrange themselves differently and the process time recommended for fresh foods will not be enough for the already canned foods. Underprocessing can lead to foodborne illness or at the very least, spoilage and loss of product. You definitely could not just transfer the food and "seal" the jar. You would need some heat treatment known to destroy any organisms transferred with the food.
(2) The expense and time of recanning foods far exceed the cost savings of bulk or large-quantity packaged foods. To re-can food, you now add the expense of a jar and lid as well as the energy to re-can the food.
(3) Most likely the quality of the food will be greatly reduced in canning the food for a second time. The heat of canning does cause loss of some nutrients, and a second round of canning will further reduce the nutritional value. Textural changes from heating will be added to those already produced.
Without tested processes for re-canning foods, there is no way to know how to reduce the canning process and the default (although not a recommendation) is to process for the full time and temperature as if starting from scratch. When you consider you are not even saving money and resources, it does not seem worth the loss of food quality to practice this re-canning of commercially canned food. Our recommendation is to not plan to do this.