You have 90 days from recording your mechanic's lien to file an action to foreclose if you are not paid. As Matthew noted above, sending a notice of intent to foreclose your lien can motivate payment. But if this does not work, you need to be ready to foreclose your lien by the 90 day deadline.
Some private commercial projects have payment bonds. If there is a payment bond in place, you can also file a claim with the surety to recover the unpaid amount. But if the principal of the payment bond (usually the GC) disputes your claim, most likely you will not recover anything from the bond without filing a lawsuit.
The contractor's license bond is another potential source of money. But keep in mind that the total of the bond is only $15,000 and under most scenarios you would only be eligible to recover is half of that (if anything). And again, if your customer disputes the claim, there is a strong likelihood that you will not see any money unless you move forward with a lawsuit.
If you still have time before your lien expires you might consider a demand letter from an attorney threatening to foreclose on the lien.
But if you are within 30 days of the lien expiring, you should seriously consider retaining counsel to prepare a lawsuit to foreclose the lien along with other potential claims such as breach of contract and violation of prompt payment rules.
If you require legal assistance email me at ryan@huntortmann.com to schedule a free telephone consultation.