Hi Veronica, I need to clarify first, that personally I do not currently own or work with any type of kiln. I do have some jewelry making friends who do, so I asked them. The general consensus is that unless you know exactly if, or with what, the porcelain painting is coated (lacquer, sealant, etc.), you would just have to try one to find out.
Most painted porcelain can be heated; however, the colors may darken or burn. If there is a sealant of some type to protect the painting, that would be the main problem, as many of them will melt or burst into flame! Finished, glazed pottery can be incorporated into materials such as PMC and Art Clay and heated with no problems.
Answer contributed by Dale "Cougar" Armstrong