Getting Error (snapshot Too Old) - Restructure Code?

we are getting "snapshot too old" error when we executing a procedure. The error details are as below:

"ORA-01555: snapshot too old: rollback segment number 208 with .."

The code framework is below. basically we are having 3 cursor to select data and the base tables seems to update frequently. hence we understood that this error might come. if any other better way to restructure the below code framework.

Create or replace procedure proc1 as
CURSOR C1 is
select a from tab1
CURSOR C2 (p1 VARCHAR2)
is
select * from tab2;

[code]...

Since DBA not willing to change UNDO_RETENTION and other UNDO* parameters, we need to work around with restructure the code.