The Valve Index is a tethered PCVR system where heavy physical use (movement, cable tension, sweat) drives wear more than "age." Common repair triggers include cable tether problems, controller drift, and tracking/base-station issues. If your issue is confined to a replaceable accessory (tether cable, controller, base station) and the fix is under the threshold, repairing is often the best option because it restores the system without requiring a full platform change.
Replacement becomes more reasonable when the headset itself develops panel defects, persistent tracking instability across multiple rooms, or multiple components are failing at once-those scenarios can push total cost near the threshold quickly. Also consider opportunity cost: if newer headsets materially improve comfort or resolution for your use, a large repair may be better spent toward an upgrade rather than extending a system that's already borderline for your needs.