Dear himatbhai,
Option 1: Go for Sprinkler/Rain Gun. This will reduce your water requirements very much.
Option 2: From your posting, I understand you have dug the well. Even if there is no water, do not panic. You should save the entire rainwater in your 5 acres and direct it towards your well, I am sure your well will recharge very soon.
Option 3: Do not go for water hungry crops and try to identify the crops which need very limited water.
Option 4: Instead of cultivating the entire 5 acres (either groundnut or wheat), go for a small area (1-2 acres depending on the water availability) for cultivating either groundnut and wheat. The other areas can be utilized for growing trees/vegetables which will bear fruit and the need for water is very less. For eg., paper is produced from Casuarina equisetifolia which does not need much water at all.
Option 5: Approach your Kisan Vikas Kendra and get help.
Best of Luck!!!
Regards
Padmanabhan