The only mention of illegal immigration I could in Platform Issues was under National Security - Secure Borders in the new RNC request.
The Republican National Committee is requesting input on the Party Platform:
"The Republican Party is seeking your input as we develop the policies and principles upon which we should stand for the next four years. On this website, you can share your thoughts, participate in polls, and communicate directly with the policymakers who will be shaping the party's agenda. All comments and feedback will be reviewed and taken into full consideration as we prepare for our convention in Minneapolis-St. Paul."
However "illegal immigration" search does come up with 88 hits. I briefly looked through the first 40 (the last 2-3 days) Virtual every one voiced the NO AMNESTY opinion (meaning "immigration reform" a.k.a. Sale of Citizenship to the lowest bidder)
In the last 30 minutes 8 more posts - most virtually identical. "I want the Republican Party to get serious about ending illegal immigration and reducing overall immigration numbers. I hope the GOP platform includes attrition through enforcement measures and an end to chain migration policies."
They may have underestimated their members distaste for amnesty - hopefully they'll listen and the platform will again reflect the opinion of the people. See articles below on Platform history.