Hi Will,
I'm sure someone with a bit more experience than me can chime in, but I'm almost 100% certain that since the 1400 has the carts on the print head that they are sufficiently agitated simply by printing. From what I've read of Paul's reports in the past it is the wide format printers or CIS systems where the ink doesn't move that settling is a problem. So I think refilling in the printer is fine, especially with your printing frequency.
I only asked because I had let a printer with its carts sit unused for about 9 months...
Ken