Switches for PVS-14 are quite special and have a pull-to-IR function built in. If you're not sure how to go about soldering on a full switch, then always go to someone like TNVC for a replacement as you'll save money ( and damage to the monocular ) in the long run.
Typically, these switches are not cheap. Even if you buy the switch direct from the manufacturer, the cost reflects the complexity.
For those who just need a cheaper solution, or are DIY specialists, you can get a generic switch from the same manufacturer for around $20 which you can hand-wire up, and set for off/on/IR. The difference is that you will no longer have the pull-for-IR setting, and turning the switch all the way on will turn on the IR also - and there's no warning that you will turn on IR until it's on.
This kind of repair is cheap and inexpensive, but should never be used for any tactical ( including SHTF preparation ) purposes.
Regards
David