The cliche is always going to be "Can you afford not to take out the insurance?" If you don't have insurance and you die then the house will be sold to pay the mortgage off leaving your son what ever is left.
You said that you put the insurance in place for a specific reason previously and from what you are saying, this specific reason still stands but it could be issues with your health that may stop the insurance being put in place.
I am not an insurance underwriter and would never pretend that I know how this breed of animal works but from past experience I would say that the fact that you are taking medication for potential depression does not mean that you will be declined outright. There is so much more understanding about medical conditions and illnesses now than there was even just 5 or 10 years ago. In many cases where someone had been diagnosed with cancer it was unlikely even just 10 years ago that you could ever get life assurance again and yet I have recently just gained a new life policy for someone who had breast cancer only 8 years ago...and there was no addtional loading on the premium. Depression now has a far better understanding tha even a few years ago and is far better managed now than a few years ago where the stock answer was Tamazipan or some other heavy anti depressant and it is now the most common ailment that people see their GP about nowadays and is often treated with just a good dose of healthy exercise (I do not pretend that this is the only methiod of treatment)
Having just spoken to one of the life companies I use they have told me that often if your condition is well controlled and assuming you have no other medical issues or complications that could be linked to the medication or other medical problems you may have then there should be no issue with gaining life cover although you may have some problems with getting critical illness cover. If it is just the house you are trying to protect (with a little extra for income) in the event of your death and you do not requirte the critical illness then i would speak to the insurance company again.
It may also be advisable to speak to a mortgage broker or financial adviser regarding your needs and they may be able to place it in a better order for you plus they can also look at putting the policy into trust for you
If protection your house is important to you and made you feel that the house was secured for your son then I would definitely look to put in back in place again. I would approach the life assurance company again and let them do what they need to do so far as getting the GP report. It may possibly end up in a decline but unless you are planning on applying for more life assurances over the next few years then this decline is not really going to matter too much, it may end up with an exclusion to certain events for the policy, it may be that the copmpany places an additional loading onto the premium to cover any addtional risk they think you may pose but it will always come down to the fact of whether you want to keeop the protection on the property or not and if it is that important then the cost (within reason) will not matter.
Good Luck, let me know how you get on