There is a cheap solution: normally its possible to hammer the pins
deeper.  This can be done if the pins are not too loose, and it should
not be done without prior advice of a piano technician.

Repinning and then replacing with the old strings is, except for the
bass strings, not a good idea.  If you want to do it on your own you
will need the help of a piano shop, in order to find out the diameter
of the new pins.  The same shop is able to supply you with those new
pins and the new strings.

Renewing the pin block is asking for well-trained hands, and is not
an easy job for an amateur.

Jan Kijlstra
The Netherlands