RIP has several meanings in computing, but here I am almost certain that it means the date on which the raster image processing was done. This operation, also known simply as rasterizing, is a normal stage in preparing a page for printing.

The verb "to rip", as in Louisa's reference, normally refers to something quite different, which is irrelevant here: converting an audio CD to some other digital format, or decrypting and storing a DVD, or converting a digital to an analogue format. It is also sometimes used to mean rasterizing, so this could be called the "ripping date", but that expression would not normally be understood in this sense.
http://www.pcmag.com/encyclopedia/term/50547/ripping

Louisa's reference to a "rip date" refers to converting the tracks on an audio CD:

"I want the current date to be populated to each track that I rip, automatically."
https://forum.dbpoweramp.com/showthread.php?16708-How-do-I-a...

The initials RIP can mean:
Raster Image Processor
Routing Information Protocol, or
Remote Imaging Protocol
http://www.pcmag.com/encyclopedia/term/50545/rip

But here, as I say, the only relevant one is the first. It is the date on which the artwork was rasterized, using an RIP:

"rasterize
To prepare a page for display or printing. Rasterization is performed by a raster image processor (RIP), which turns text and images into the matrix of pixels (bitmap) that will be displayed on screen or printed on the page. Various conversions may take place. For example, the mathematical coordinates of vector and outline fonts as well as vector drawings must be converted into bitmaps. Existing bitmaps may have to be scaled into different-sized bitmaps.
Unless output is printed on a vector graphics plotter, which literally draws the illustration with pens, all text and graphics must be rasterized into a bitmap for display or printing."
http://www.pcmag.com/encyclopedia/term/50198/rasterize