Hi
In general, lock in period cannot be enforced legally and the Lessor is liable to make a claim only for the period in which the premises is vacant.
Also in your case, since your business is NOT doing well, you are legally entitled to issue a termination notice to the Lessor prior to expiry of lock in period.
In general, parties circumvent the lock in period clause , by not paying rents, maintenance charges etc and thereby forcing the lessor to let go of the tenant.
Ideally the lessor, should permit you to vacate the premises after you serving notice and notice period thereof as in your case, you are openly stating your inability to perform the part of contract (i.e tenancy in your case) and as such the other party cannot take undue advantage and claim rentals for lock in period from you and more so when you are not generating sufficient income to sustain the business.
So in order to ensure a Win Win Situation for both the parties ,
1) Issue notice to Lessor of vacating the property, citing your inability to pay rents in forthcoming months(i.e after expiry of notice period) and Ask for a refund of security deposit and
2) In event of Lessor(shopping mall) not agreeing to above, ask the shopping mall to permit you to sub lease/ fully lease the premises to an alternative tenant at your cost.
If the Lessor does not agree to the above mentioned Win Win Situation, then you should come to court and challenge the lock in period itself ( no lessor would like to get the property locked in court case) and i am sure your lessor will realise his folly and let go of you.
Hope this information is useful