Depends on your version of Access. The Replace() function was
introduced in A2000, and made available in Queries in 2002 (and, I
believe, in some recent A2000 service packs).
If you're using ADO (as it appears from the %; JET uses * as a
wildcard) try a query like
UPDATE yourtable
SET field1 = Replace([field1], ",02", ",2005")
WHERE field1 LIKE "%,02%";