I have different Python list variables(data1, data2, data3 ect) containing data which I want to put into an already existing excel sheet. Presently My loop goes like this.

for row, entry in enumerate(data1,start=1):
  st.cell(row=row, column=1, value=entry)
  work.save('sample.xlsx')
for row, entry in enumerate(data2,start=1):
  st.cell(row=row, column=2, value=entry)
  work.save('sample.xlsx')
for row, entry in enumerate(data3,start=1):
  st.cell(row=row, column=3, value=entry)
  work.save('sample.xlsx')
for row, entry in enumerate(data4,start=1):
  st.cell(row=row, column=4, value=entry)
  work.save('sample.xlsx')
for row, entry in enumerate(data5,start=1):
  st.cell(row=row, column=5, value=entry)
  work.save('sample.xlsx')
for row, entry in enumerate(data6,start=1):
  st.cell(row=row, column=6, value=entry)
  work.save('sample.xlsx')
for row, entry in enumerate(data7,start=1):
  st.cell(row=row, column=7, value=entry)
  work.save('sample.xlsx')      

Once my Python script runs, It will store the data from the 1st row. If I am again running the script I want the new data to come below the available data

How to do so?

Try using:

sheet.max_row 

It will return the last row value, you can start writing the new values from there:

max = ws.max_row
for row, entry in enumerate(data1, start=1):
   st.cell(row=row+max, column=1, value=entry)