Replace Hard Drive and retain all apps and data

Here's the guide on replaceingthe hard drive: Sostituzione hard drive del MacBook Pro Unibody 2.53 GHz da 15", modello metà 2009

Next, the drive will need to be formatted (GUID & Mac OS X Extended).

To do this you will need either a external enclosure or USB to SATA adapter or Universal adapter Universal Drive Adapter.

Enclosure http://www.ebay.com/itm/282243318167?_tr...

USB to SATA http://www.ebay.com/itm/152451267898?_tr...

Next, with the new drive in the machine, hook up the old drive with one of the options I gave to a USB port. Boot the machine - it will go to the external as that's the only system available. Go to Applications > Utilities > Disk Utility

Now, Format the new drive.

Next, You need an operating system, the same or higher than what you currently have. I'd go to Sierra. If you do not already have it on your drive, go to the App Store and download it.

Now install it onto the new drive. This will give you the new system and the repair option partition.

Next, reboot from the new drive. Hold the Option key down on reboot and select the new drive.

Now, this will initiate the set up procedure on the new drive. You will be given the option to Migrate from the old drive. Select it, migrate your choices and User.

Now reboot and you are set up.