It is safe to use the drops 4-5 times per day. However if you are not having any relief in symptoms even after using the drops for 3-4 weeks then you should visit the nearest Ophthalmologist for a detailed evaluation of Dry Eye Disease.
Next Steps
In my opinion putting the drops twice daily won't be enough. Try putting it 4times per day.
Health Tips
Don't use the bottle if it's opened more than a month ago or in case of any changes in drop colour.