You don't need U1. Both U1 and U2 have the same nominal current limit. Just readjust R1.

You don't need D1, with its variable voltage drop, but in its place, you would need a diode from U2 out to U2 in, to power the input in the event that you connect the battery without input power.

Once you have removed D1, set U2 to deliver 13.8v. This voltage will safely float sealed lead acid indefinitely.

Heatsink U2 appropriately for its expected dissipation. While the current limit of the TO220 version is specified to be >1.5A, it can often be higher, I've seen 2.2A. The 317 is thermally protected, which means if it gets too hot, it will shut down for a while while it cools down, so an inadequate heatsink means not a fried 317, but a slow charger. You can reduce the expected dissipation by increasing R1, which moves the heat from U2 to R1. 

With those voltages, you might want to consider making R1 an incandescent bulb. The strong positive tempco of the filament resistance means they are sort of constant current components, much more so than a resistor. For example, a 12v 12 watt halogen will draw the thick end of 1A at a large range of voltages across it. A bulb has this neat trick of being able to lose a lot of power in a small space safely.

Some sealed lead acid cells state that you can use a higher charge voltage if you time the over-voltage carefully. Doing this will result in a quicker full charge. Check the book of words for your specific cells carefully to avoid destroying them like this.