If only....
Getting neurons to regrow or fuse, particularly in the central nervous system, is one of the biggest open challenges in neuroscience. If it were actually that easy, spinal cord injuries would be a thing of the past.
What you say is theoretically possible if the neurons weren't living cells and humans had the technology to reconstruct the brain's wirings. Your body isn't going to figure out which "wire" connects to which on its own.
For patients with really severe epilepsy (where the seizueres are causing slips and falls), one possible treatment is to cut this bundle to prevent the epileptic activity from spreading across both hemispheres. You basically just slice through them with a knife. Since neurons are very small and delicate, it's extremely unlikely that the membranes (essentially drops of oil) would reform in a way that would permit them to carry information.
Since the corpus callosum contains most of the inter-hemispheric connections, cutting it is often sufficient to prevent the siezure from spreading (and also to produce weird split-brain phenomena). However, there are a few other locations where there are cross-hemispheric connections. The anterior and posterior commissure are two other "interconnects." There may also some much more indirect interactions through subcortical structures.