Is It Worth Keeping 97 Chevy Venture w/143K miles??

What is your question?

I have spent over $8K dllrs in maintenance on my 97 Chevy Venture in 6yrs. I have put a rebuilt trani in 04 which was the most expensive part & cylender heads in 10'. This is our family van and we have taken many raod trips, the farthest into Guadalajara Mex. I have kept it up becuase it takes us everywhere However, I dont know if it's worth keeping it up now that is reaching 143k miles. Or when do I stop putting money into it???