Everyone is giving you good information.
My bot is one level lower, earns roughly 5 digits per 1-11 mission and 4 on average per level mission.Shinu
However you have to consider the tactics you are using and why you are using them.
With Repair you need to be in the 1-11 fights and with larger levels on your side. Repair does not work on yourself. Repairs on same/lower levels will work great, but you will not get high XP yields. This build (Battle Station) uses INT as its modifier
With Strafe you need more targets (again 1-11), or more chance to fire off strafe. High Courage and Speed will help with this. Also high firepower will help with Strafe.
Psychout brings up a good point about rammers, however if you are building a glass cannon (All damage/Repair no defense) then points into strength will take away from your other tactics.
Personally (this is just me) I would look at Absolute_Zero's Strafe/Repair and Zordon's Strafe Repair.
I would also personally reduce the firepower down to 5 or 3 and boost the Courage up to 6 or 7 and int up to 3 or 5.
If you wanted to build a damage spec for lower/mid level game and then do repair starting lvl 6 I would drop the int, drop the repair tactic and put points into strength, end, rnk (2 pts) and help reduce the damage taken. At 6 you will have 9 points to build your repair tactic up solid while having a solid strafer to keep you in the damage field.