Probably, there are lots of easy ways to do this, but I must use incremental export and import.
The following is the brief description about the situation.

machine A and machine B have an indentical structure.

DB1 is a primary database and DB2 is a cloned database.

on Sunday, I took a full export from the DB1 and imported into the DB2.(full.dmp)
( I already imported data into the DB2)
on Monday , I took a incremental export from DB1.(incfile.dmp)
on Tuesday, I want to import incfile.dmp into the DB2.

Can anybody tell me the right syntax and procedure?

imp system/manager inctype=system full=y file=incfile.dmp
imp system/manager inctype=restore full=y file=incfile.dmp