I recently needed to update my signage when I got my brokers license.  I also had signs old signs with and without my designations from various times in my career.

An old trick I used in the old days of helping political candidates is to match the signs color and have the local sign maker cut vinyl tape to cover the old lettering.  Then have them run new vinyl lettering to put over it.

I applied the tape and lettering myself.  If you are not comfortable doing it yourself you can have the sign shop do it.  This also works on your car magnets.

For about $150 I rejuvenated about 25 custom signs and car magnets in one evening.