Do you know where your Crohn's is located? If you have Crohn's only in the terminal ileum, then the Entocort can do the job by itself. And it does take a few weeks to reach full strength.
But if your Crohn's extends well into the colon, then the Lialda can help, as well. Lialda is a new medicine, FDA approved only this past January.
You could try replacing the Lialda with Asacol, which is similar to Lialda (targets mainly terminal ileum and colon) or Pentasa (similar, but targets entire small intestine and then colon, but less of it gets into colon than Asacol and Lialda). These are all mesalamine meds...basically the same, but targeting different areas. And formulated differently, so some people can tolerate Asacol better than Pentasa or vice versa.