How do I update partial value.

Example:
I have emp table with column hiredate, Hiredate has values like
11-AUG-98
10-OCT-88
12-OCT-88
11-OCT-89
.....
.....

I want to keep the date same but only change year where year = 88 to 2001.
so Result will be as shown below

11-AUG-98
10-OCT-01
12-OCT-01
11-OCT-89
.....
.....

Thanks in advance