I'm afraid in most circumstances replacing the boot isn't going to help.
The boot is not intended to hold power steering fluid in, so if you have a leak it is likely coming from a seal in the rack itself...which means a replacement or rebuild is the only way to repair.
Replacing the rack is not for the faint of heart...it's a relatively big job and working the rack out takes a bit of wizardy/contortionism. I believe there is a how-to floating around here that talks about the specifics, but I would not recommend unless you have a lift and a lot of confidence.