I don't know if those bolts are replaceable, but bolts wear out. Some are meant to only be torqued once, others can handle a few uses. Reloader, Bigunit and I were discussing this recently and with the amount of times we've disassembled the front end of our trucks we're going to start replacing UCA pinch bolts, shock bolts, etc.
I didn't see a mention of putting any threadlocker (Loctite) on those threads. Start with blue Loctite and see if that helps. If you're putting on new bolts and things are still backing off I suspect you are not torqueing enough and/or you'd benefit from threadlocker.