A chip that will not scan has usually moved, not died
Microchips are implanted between the shoulder blades, but they do not always stay there. Over months and years a chip can drift down the chest, over a shoulder, or along the side, and a quick pass of the scanner over the usual spot then finds silence — from a chip that is working perfectly well a few inches away. Genuine electronic failure does happen, but migration and a hurried scan are the more common explanations, and they are far cheaper to rule out.
Scanners matter too. A scanner with a low battery, or one swept too fast and held too far from the body, can miss a readable chip. So the first move is not replacement; it is a better search.
Getting a scan that settles the question
Ask a veterinary practice or shelter to scan her slowly over her whole body and neck, close to the skin, in overlapping passes, ideally trying a second scanner if the first finds nothing. Note where the chip is found if it has migrated — that location is worth recording and telling anyone who scans her in future, such as a new vet or a shelter if she is ever found stray.
While you are there, have the number read aloud and compare it digit by digit with your registration paperwork. A mismatch can mean the record you have been updating belongs to a transcription error made at implant, which is its own fixable problem.
If the chip truly cannot be found or read
When a thorough scan finds no working chip, discuss a replacement implant with your vet at the same visit if she is well and settled — it is a quick injection-like procedure for most cats. Register the new number before you leave the building if you can, in your name, with your current phone number and address, and then test that the registration is live by looking the number up or calling the registry.
Contact the old registry as well and ask them to note the replacement against the old number. If the old chip ever does read again — in a deeper scan, say — that note is the bridge that gets a finder from the old record to you.
Checking the registration you already have
A working chip with stale details fails almost as completely as a dead one. Once a year, and after every house move or phone change, confirm the registry record: your number, an alternative contact who will actually answer, your address, and her description. Owners are often surprised to find a chip still registered to a breeder, a previous address, or a phone number retired long ago.
Keep the chip number itself somewhere you can reach without digging — in her records, in your phone, and with whoever cares for her when you travel — because quoting it accurately is what lets a shelter reunite you quickly.
Backing the chip up with identification that shows
A microchip only speaks when someone scans her, so visible and documented identification covers the gaps: a collar tag where she tolerates one, her details current with your vet, and clear recent photographs kept ready. Layered identification means one failure — a dead chip, a lost collar — never leaves her anonymous.
That layering is easy to keep tidy with KinsLe, because a Pet Pass works as her verified ID card, holding her identity and your contact details ready to show anyone who finds or treats her.