My Mother 80 Yrs Old Whom Has Moderate Dementia, Had

My mother 80 yrs old whom has moderate dementia, had bilateral PE 10 month ago, she cured and now she is under Warfarin (3-4 mg/day) to keep INR between 2-3 since that time, pls advise if she could use Aspirin instead of Warfarin. she had also PEG tube to avoid aspiration recurrent puenmonia putting in mind that she has very less movement.