Just eating food with D3 in it is insufficient to maintain a healthy level and no good for restoring the levels to a normal level. You need daily exposure to sunshine as well, or supplementation, in the absence of sunshine to maintain acceptable levels.
Here's some info from NIH: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
If this is a concern, I would get a vitamin D test done and have it assessed by a doctor who may then put you on high-dose supplementation; you cannot buy tablets with the required levels to restore deficiency - they are prescription-only. Not in the UK anyway,
I've been through this process recently with vitamin D and learned this stuff from the people treating me.
Go see your doctor.