How much over is that with respect to your REIT allocation itself - 10% or more over? For example, if REITS are supposed to be 5% of your portfolio, but they have grown to 7%, that's 40% over where you intended them to be. I tend to trim under those circumstances.
Do you reinvest the distributions? Not reinvesting distributions is another way to trim a position, but it might not be enough.
Trim, then let them shrink below allocation (if they ever do), and after that add money to bring them back up to allocation - that's how it is supposed to work. Otherwise you aren't getting the benefit of rebalancing.
Audrey