Solar battery

This is not a vehicle question, but this is about the only place I know where people have real world experience with batteries.
I have been running a small PV set for about 3 years. It is rated at 45 watts. I use a marine trolling moter battery for power storage. It was cheap and I have had experience with that battery, so I went with what I know. The system was installed as a backup and test uint. It runs a light and fan ( and sometimes 12V to 120 V converter ) in one room. The battery is outside and has been through somewhere around 1000 charge discharge cycles. I am told by the local vendor that is about as long as I can expect the battery to live in the Florida heat. It has cycled somewhere around 1000 times.
I need to replace it. Any suggestions?
Would like to store 3 days of power in the battery, about 100 amp hours,and have it live with the current battery control, or have a cheap replacement controler. Perfer something I can get close so I do not have to ship, but if I can find a good enough product, I can ship.