When does dell typ. refresh the laptop line? (xps z-series)

maybe i can revise my question-

Is it a reasonable idea to wait to buy one right now if the last ones were released a year ago, with the expectation that a product line refresh could be around the corner.
I wont need it till the end of summer.

Some details of the refresh have been leaked, and we are currently in the middle of Dell's "last call sale" on that line, so yeah I think it's likely that a refresh is right around the corner. I'm thinking it could be right after this sale is over, but I don't know that for sure.

You may consider buying during this sale if you think the deal is good enough, or wait until the refresh which will have Ivy Bridge and probably newer NVIDIA graphics.