I am not aware of a script. But the renewal takes places on the mgmt. There you renew the cert and push it out via policy push.
That is why I don't think you can run a script on the box itself.
Now the steps are not to bad, if I assume you renew it on the fw object in Smart Console and press the renew button, correct?
You can also think about to extend to cert time from 1 year to 3 year: https://support.checkpoint.com/results/sk/sk176527
This will save a bit of work until there is something new as PhoneBoy posted.
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