U can't increase allowance in this way...
U need to approve with some other way like from frontend or depositer need to directly call token approve function..

Since approve function increases allowance of the msg.sender.. so if u call it from ur contract then msg.sender is ur contract..

So it will be like increasing ur contract allowance of ur contract token balance not increasing depositer allowance of token balance..

So for example if u call approve function in ur smart contract for 100 LINK tokens...

Then Link token allowance will be:
allowance[address(this)][address(this)] = 100

allowance[msg.sender][address(this)] = 0

So it doesn't make sense to delegate ur contract link token balance to ur contract itself..