1. Before dropping the table run the below script which will prompt you to input the table you are about to drop and keep the output.
select 'alter table ' || cc.table_name || ' add constraint ' || c.constraint_name || ' foreign key(' ||
cc.column_name || ') references ' || cc_r.table_name || '( ' || cc_r.column_name || ');'
from user_constraints c, user_cons_columns cc, user_cons_columns cc_r
where c.constraint_type = 'R' and
cc.constraint_name = c.constraint_name and
cc.table_name = c.table_name and
cc_r.constraint_name = c.r_constraint_name and cc_r.TABLE_NAME = '&ref_tab';
2. drop the desired table
3. recreate that table
4. run the output scripts you get from number 1