Unfortunately hardware types are only possible to upgrade to in the HW Config, if the basic type already exists in the STEP7 version.
The CPU 6ES7315-2FH13-0AB0 requires STEP7 v5.4 + SP2 or higher.
As an alternative, you can try the CPU 6ES7315-2FH10-0AB0 which requires STEP7 v5.3 + SP3 or higher.
Normally you can program a newer CPU by using the previous type, if only the basic type is the same.
The more proper solution would be to upgrade your STEP7 to the current version 5.5+SP1.