TestComplete question

I am assuming here that Valor:20 is a string

first, have a variable to save "Valor: 20"

then use aqString methods to pick that string apart and get the 20 part 

https://support.smartbear.com/testcomplete/docs/reference/program-objects/aqstring/methods.html

now convert that string 20 to a number 20 using aqConvert and save that number 

https://support.smartbear.com/testcomplete/docs/reference/program-objects/aqconvert/strtoint.html

refresh your page and save the new Valor string in a new variable

now pick apart the new string and convert it to get the 21 and compare it to the 20 to make sure it is +1

Try this and if you get stuck, let us know here and we can help some more!