Modifying check constraints

Hi all:

Let's suppose I create a table with a CHECK constraint, like:

CREATE TABLE blabla (id int, tipo varchar(8),
CHECK tipo IN ('tipo1', 'tipo2', 'tipo3'))

Can I change the CHECK constraint afterwards? For example, can I
add another value that "tipo" can have, or I'd have to recreate the
table?

Paulo Jan.
DDnet.