Complete a Regular Expression for Combobox

I need someone to complete a regular expression for me. I'm almost there and just need one final push, unfortunately I'm a novice when it comes to regex. I'm creating a combobox type field that autocompletes from a set of values. Each value can only be selected once, so I'm using regex to filter out values that have already been selected. If you look at the "Post Project" page on Freelancer, the "Skills" combobox on that page works exactly the same way as what I am trying to accomplish. I've got it to work for the most part, but I am having trouble with values that have spaces in them. I will provide a link to my project on jsFiddle once I have accepted a freelancer to make the necessary changes. I expect it should take no more than 10 minutes if you know what you are doing. Thanks!