Legal Question in Civil Litigation in California

The answer will depend, in large part, on what your contract says. In the absence of contrary provisions, your damages will include all the rent that remained to be paid under your lease, minus the amount that any new tenant will pay up to the date on which your lease would have ended, plus all the expenses your landlord reasonably incurred to find the new tenant and prepare the space for them. (The landlord is required to use reasonable efforts to re-lease the space.)

If the upgrade you describe was required by law then you probably don't have to pay for it -- unless the *reason* it was required related to the way you were using the space. Even then, I would need to know more about the facts before I could give you an answer.

Whether you must pay the landlord's legal bills will depend upon what your lease says. Most leases do contain language requiring the party who breaches the agreement to pay legal fees and costs which the other side reasonably incurs while enforcing its rights under the lease.

Having breached the lease, you are not entitled to reclaim the space. The landlord may agree to let you have it under a new lease, but he is not required to do so. The fact that you have already breached one lease will probably make her reluctant to trust you with another.

The best way to minimize your damages would have been not to break the lease. Failing that, you would have been in a better position to negotiate while you were still in the space. You don't have such great bargaining position now, but you may still be able to work something out with the landlord.