Take two or three days off from even THINKING about the NCLEX then make yourself some flash cards with lab values on them so others can drill you. You'll get em'.
Link similar values together. For example: Normal Ph is 7.35-7.45 and Sodium is 135-145; PaCO2 is 35-45 and Hct (hematocrit) is 35-45% (see the connection?) There's more like that so look for it.
If a value is a close one to another or to something you can relate it to and has a variety of 'normals' depending on where you get the information remember it in a relation to another by making the numbers close. For example: Bicarb is one that seems to have a variety of 'normals'. I remembered it as 24-28 because those are two specific dates to me in relation to my husband and I was able to tie it that way. Plus we have 3 kids and when abriviated Bicarb has a '3' -HCO3 - in it so that reminded me that it was the one related to my husband!
As long as you can recongnize a normal value or it's general area then the abnormal will stick out to you or vise versa when taking the NCLEX and that will help guide you to the correct answer.
Good luck! I had trouble with this too, it's a toughy.