Hey As per Rule Number 138(10) Validity of EWAY Bill are as follows:-
Upto 100 KM - VALIDITY 1 DAY
For every next 100 km or part thereof - one additional day.
Means for 2500 KMs you have 25 days.
Also if think or due to exceptional circumstances unable to complete the movement within the said period, you may generate another eway bill by updating the PART B of FORM GSTEWB-01
HOPE YOU GOT THE ANSWER