I am sorry to answer you in english:
1. As told you BeWorld changing the coin battery CRC 2032 for other, the batteries have a life of 5-10 years, clean the battery box because the copper contacts can be dirty with a green rust, you can clean this with a contact cleaner or with alcohol and paper, but never with water.
2. Also in the worst case, the clock has problem with harware, in this case you can use my tool BootClock, made for hardware clock problems, save the current hour in ENV: and you can recover the last hpur saved.